Obligation of Zimmun
- If three people eat together are obligated to make a Zimmun before benching (making Birkat HaMazon).  Chazal based it on the pasuk “גדלו לה" אתי ונרוממה שמו יחדיו”  and “כי שם ה" אקרא הבו גודל לאלוקונו” .
- Most authorities consider Zimmun to be a rabbinic obligation. 
- Zimmun could be said in any language as the purpose is to introduce the benching orally and join the group together to praise Hashem. 
- Some say that answering Zimmun is considered one of a person’s hundred Brachot every day. 
- When we say the zimmun Sephardim have a practice of starting “הב לן נברך למלכא עילאה קדישא”. Then for Shabbat they insert “ברשות שבת מלכתא” and for Yom Tov “ברשות יומא טבא אושפיזא קדישא”. For Sukkot the practice is to insert “וברשות שבעה אושפיזין עלאין קדישין”.
- Some say that one should ask permission from the wife of the host in the zimmun as well.
Who Should be Given the Honor of Zimmun?
- If there are guests, the homeowner should honor one of the guests with zimmun and he can even choose one of them who isn't the greatest talmid chacham.
- If there's no guests, a talmid chacham should be given first right to lead zimmun, afterwards a kohen should be given the right. If the kohan isn't a talmid chacham and there's also a talmid chacham there the talmid chacham may not say that he's giving the zimmun to the kohan based on rights of a kohan but he may give him permission to do the zimmun.
- There is no difference for zimmun if the person leading zimmun ate a kezayit of bread and isn't full or whether he's full. Similarly, there's no difference if he ate and drank or just ate. That is only for leading zimmun but not if one person is actually being motzei another person their obligation in Birkat Hamazon.
Who has the obligation?
- There is only an obligation to have a zimmun if three or more people eat together. The three conditions to be considered “together” is that those who are eating 1) eat while seated, 2) sit at one table, and 3) start or end the meal together.  They are considered starting together if they all start to eat the first kezayit of bread while the others are still eating that first kezayit.
- A person eating with his family is considered one eating together to be obligated in zimmun even if they aren't eating at the same table.
- People eating together at a simcha or any other occasion are considered eating together even if they aren't eating at the same table.
- If in a school or yeshiva, the students go to lunch at the same time, the group can make Zimmun together even if they sit at separate tables as long as they can see from one table to another. Even if they don’t have enough at each table to make their own Zimmun of ten, they can join together to make a Zimmun of ten. However, it’s preferable that they one time actual say verbally that they intend to eat together. 
Zimmun When They Didn't Establish Together
- If two groups ate in different places in the same house and they could see from one group to another, if they have intent (when they began the meal) to join for Zimmun they may join, however, if if they didn’t have intent, then according to Sephardim they may not join for Zimmun, but according to Ashkenazim it’s a dispute whether they may join for zimmun. 
- If three people aren’t obligated to make Zimmun as they didn’t join their meals together sitting, on the same table, and starting or finishing together they may not have a zimmun. Some say that if they sat together but they just started and ended at different times they that they can have a zimmun together.
If a Member of the Zimmun Left or Benched
If a Member of the Zimmun already Said Birkat Hamazon
- If three ate together and were obligated in Zimmun and one forgot about Zimmun and said Birkat HaMazon then the other two can say zimmun with the third.  However, if one of the group already answered Zimmun with another group he can’t answer another zimmun of three. 
- If three people ate bread together, and two forgot to wait for Zimmun, the other one can not do Zimmun with the ones who already Benched. 
- If four ate bread and two forgot and said birkat hamazon the other two can create a zimmun with one of the ones who already said birkat hamazon.
- If three people ate together, two ate bread and one ate a Kezayit of something else or drank a Revi'it of a drink (other than water) are obligated to make Zimmun. 
- If one of three only had a Kezayit of another food or a reviyat of drinks, and one of those who ate bread forgot to wait for Zimmun and Benched, the other one who ate bread can no longer make Zimmun. 
- If one of three only had a Kezayit of another food or a reviyat of drinks, and the one who didn’t eat bread forgot to wait for Zimmun and made Bracha Achrona, the other two who ate bread can no longer make Zimmun. 
- If there's a zimmun of ten and one already said birkat hamazon, according to Ashkenazim they can still recite a zimmun with Shem even though the one who already said birkat hamazon doesn't fulfill his obligation everyone else does. In fact this works even if three already said birkat hamazon. According to Sephardim they can not make a zimmun with a shem.
When is it Permitted to Leave?
- If three people ate in three different groups of three they shouldn't leave their groups and form their own zimmun because doing so will invalidate their original groups.
- If three people ate in three groups of four or more people they can leave their groups and form their own zimmun because their original groups will still have their own zimmun.
If a Member of the Zimmun Left
- If someone in a group of four and one left and they did zimmun while he wasn't there he is exempt from zimmun and he can't later join a zimmun. The same is true if he was part of a group of three and he left and someone else replaced him and they did a zimmun without him, he lost his obligation of zimmun.
- If three ate together and one person left he could be called back and Zimmun could be said even if he’s standing by the door next to them, however he should say Birkat HaMazon where he ate. However, if ten people ate together and one left he should be called back and everyone should sit down for Zimmun. 
A Zimmun of Ten
- If ten people ate bread together, they are supposed to add the word Elokenu in the Zimmun.
- If seven people ate bread and three people ate a kezayit of another food or drank a reviyit of a drink other than water, they can join together for a Zimmun with the insertion of Elokenu. If there are only six people who ate bread they can't make a Zimmun with Elokenu. 
- According to Sephardim, one doesn't have to stand for the word Elokenu in the Zimmun.  Some Ashkenazim have the custom to stand for the word Elokenu in a zimmun of ten, however those who don't stand have what to rely on.
Two who ate together
- Three who ate together must do Zimmun and each one is not allowed to leave the Zimmun. However, if there’s six or more in the Zimmun, the group is allowed to split into two groups of three. If there’s ten then each one isn’t allowed to leave the Zimmun as they are obligated in Zimmun with a mentioning of Hashem’s name. However, if there’s twenty the group may split into two groups of ten. 
- Some say that it’s always preferable to join together in a larger group while others contend that once one is joining in a group of three or ten there’s no obligation to join in a larger group. 
- If three people ate together in the beginning or they finished together (and it’s considered as if they finished together if they still would eat something had if be brought to them) then there’s an obligation of Zimmun. 
- Two who ate together aren't obligated in Zimmun and therefore, they should say Birkat HaMazon to themselves. However, if one of them doesn’t know how to say Birkat HaMazon and the other does, then the one who knows may say it aloud and fulfill the obligation of the one who doesn't know as long as the one saying has intent to fulfill the obligation of the other, and the one listening has intent to fulfill his obligation. 
- According to many opinions it is crucial that the one who is listening understand the Birkat HaMazon. Some poskim are lenient and add that such was the minhag. 
Two Who Ate Bread and a Third Ate Other Foods
- If two people ate bread and a third person ate a kezayit of another food, some rishonim hold that they may not join together to make a zimmun, while other rishonim hold that they may join together for a zimmun. Ideally the third person should eat bread and join for a zimmun. If he doesn't want to, they can join for a zimmun of three. 
- If two people eat bread together and a third person ate a kezayit of another food, if one of those who ate bread said Birkat HaMazon without Zimmun, many poskim hold that there is no obligation of Zimmun.
- If two people eat bread together and a third person ate a kezayit of another food, if the one who ate the other food said a Bracha Achrona without Zimmun, there is no obligation of Zimmun.
Who can join a Zimmun
- Women who ate with a group of men who became obligated to make a zimmun are obligated to join in their zimmun.
- Women who ate together can optionally make a zimmun for themselves. The zimmun for women doesn't change whether it is three or ten or more women; either way they do not mention Hashem's name, Elokenu, in the zimmun.
- The Ashkenazic minhag is not to include children under Bar mitzvah for zimmun, while the Sephardic minhag is to include children of age 6 who know to whom they are saying Birkat HaMazon. Some are Machmir for age 9 in general, or, at least, for zimmun BaShem 
- Those who include Ketanim may do so for both a zimmun of three and a zimmun of ten but not Panim Chadashot or Sheva Berachot.
- The Kattan should have have bread in order to be counted for three.
- Contemporary Poskim agree that this does not extend including one Kattan regardless of the size of zimmun.
- If a Sephardi, Ashkenazi, and Kattan (Sephardi) eat bread together, they may make a zimmun if the Sephardi leads. If they're ten total, consisting of eight Sephardim, and Ashkenazi, and a Kattan, they Sephardim may make a zimmun baShem, but the Ashkenazim should answer quietly without Hashem's name in a way that no one will notice the omission.
- Three Ketanim who eat together may not make their own zimmun
- Ashkenazi Ketanim should still answer to a zimmun that they hear according to how much they ate with those bentching.
- Some say that two adult women and a female minor who eat together may make a zimmun.
- If there’s a doubt whether Zimmun was made or not (or in general a doubt concerning Zimmun) one should be strict to say Zimmun and in a Zimmun of 10 one shouldn’t add Hashem’s name. 
Eating after the Zimmun
- If two of the three people want to have a zimmun and one person isn't finished they can have a zimmun and the one who didn't finish will answer the zimmun and then continue to eat and recite birkat hamazon after he finishes eating. 
- How much of Birkat Hamazon does he have to heard before he can start eating again? Ashkenazim need to wait until the mezamen finishes Hazan Et Hakol, but Sephardim can eat immediately after they hear the mezamen say baruch she'achalnu ubituvo chayinu.
- If one of the three people is finished eating and the other two don't mind they are allowed to be nice and let the one who finished do zimmun and then they'll continue to eat after the zimmun.
Saying Birkat HaMazon aloud
- The original establishment was that the one doing Zimmun would read the entire Birkat HaMazon out loud. Nowadays, the practice is that everyone say it silently to themselves. 
- According to Ashkenazim it’s preferable to finish the Bracha before the Mezamen (one doing the Zimmun) and then when the Mezamen finishes answer Amen. According to Sephardim there’s no reason to finish before the Mezamen and if one did, nonetheless, one doesn’t answer Amen.  See further on the Birkat HaMazon page.
- If it’s difficult to listen to the entire Birkat HaMazon out loud one should at least listen to the primary part of the Bracha, which according to Sephardim is Birkat Hazimmun (the words “Baruch SheAchalnu…Chayinu”) and according to Ashkenazim is through Birkat HaZan (the first Bracha of Birkat HaMazon). Therefore according to Ashkenazim the Mezamen (even if he is Sephardi) must say the first Bracha out loud and everyone should say it silently along with the Mezamen. 
- According to Ashkenazim, if there’s a large group and those benching will not hear the Mezamen until the end of the first Bracha it’s preferable for the group to separate into groups of three so that it’s possible to hear the Mezamen until the end of the first Bracha. 
- It’s preferable that the Mezamen not use a microphone for Zimmun but rather someone with a loud voice do the Zimmun. 
Procedure and Text of Zimmun
- The Mezamen, who is leading the zimmun, should invite everyone to say Birkat HaMazon. It may be said in any language. If one wants to say this invitation in Hebrew, one should say "Ten Lanu Kos UNivarech" (if one is saying Birkat HaMazon over a cup of wine) or "Bau UNivarech" (if one isn't saying Birkat HaMazon over a cup of wine). If one wants to say this invitation in Aramiac, one should say "Hav Lan UNivarech" or an extended version of this is "Hav Lan VeNivrich LeMalka Iylah Kiddisha", which many Sephardim have the custom of saying. If one wants to say this in Yiddush, the phrase one should say is "Rabbotai Mir Velin Benchin". 
- Those who are participating in the Zimmun should answer to this invitation, according to Ashkenazim, "Yehey Shem Hashem Mivorach MeAtah VeAd Olam", and according to Sephardim, "Shamayim". 
- After the invitation, the mezamen should begin the actual zimmun by saying "Nivarech She'achalnu Meshelo" or with an extended version of "Birshut Malka Iylah Kiddisha UBirshutchem, Nivarach She'achalnu Meshelo", as is the custom of some Sephardim. 
- Those participating in the zimmun should respond "Baruch She'achlnu Meshelo Ubituvo Chayinu." 
- Lastly, the mezamen should conclude "Baruch She'achlnu Meshelo Ubituvo Chayinu."
- If one hears Zimmun but didn’t eat should answer “Baruch UMevurach Shemo Tamid Leolam VaEd” - ברוך ומבורך שמו תמיד לעולם ועד - which has an acronym בושת לו. 
- Magen Avraham 1:5, Kitzur Shulchan Aruch 42:5, Mishna Brurah 1:10,11
- Byitzchak Yikareh of Rav Nevinsal 1:5, Piskei Teshuvot 181:14 in footnote 60. Piskei Teshuvot cites this minhag based on Hitorerut Teshuva 1:88 and others. See also Rabbi Aryeh Lebowitz on the Ten Minute Halacha.
- S”A 192:1
- Tehilim 34
- Devarim 30. Gemara Brachot 45 quoted by the Mishna Brurah 192:1.
- Pri Megadim (A”A 197:2) writes that most authorities consider zimmun to be of rabbinic obligation. Chaye Adam 48:1 writes that Zimmun is derabbanan and some say it’s Deoritta. Chazon Ish (31:1) argues that Zimmun should be Deoritta.
- Zohar (Balak pg 186b) writes that it’s important to precede benching with “give us a cup to bench” in Hebrew or Aramaic to introduce the benching to bring the kedusha. Mishna Brurah 192:2 quotes this and writes the minhag ashkenaz was to say Zimmun in Yiddish “Rabbotei Mir Velin Benchin”. Kol Bo (Siman 25) emphasizes the group merit of the zimmun.
- Sefer Keysad Mezamnin 1:22
- Ben Ish Chai Korach n. 1 records the minhag to insert special requests for permission from Shabbat, Yom Tov, and the Ushpizin. Yalkut Yosef 192:1 agrees. He cites the Yafeh Llev 1:192:5 who argues that this is a real minhag and it appears as though one is believing in two gods. Also he is degrading Hashem’s dynasty by comparing it with other entities. Yalkut Yosef defends the minhag that one’s intent isn’t to compare Hashem to anything and it is just for honor to mention them. Mayim Chaim 2:17 agrees.
- Mareh Habazak 5:9 writes that one should ask permission from the wife of the host in the zimmun since it is socially appropriate and nice it should be obligatory. He explains that the asking permission in zimmun isn’t really asking permission but just an honor. See the Sephardim practice of mentioning Shabbat and Yom Tov in the zimmun.
- Shulchan Aruch O.C. 201:1, Mishna Brurah 201:4. Sefer Vkidashto (p. 173) writes that a host can honor whichever guest he likes even a non-kohen over a kohen. His proofs are Shulchan Aruch Harav 167, Biur Halacha 201, Minchat Elazar 4:49, and Mishna Halachot 3:28.
- Shulchan Aruch 201:2. The Gemara Megillah 28a explains that a talmid chacham who gives the zimmun to the kohan as a right of him being a kohen it is a disgrace to the Torah.
- Mishna Brurah 197:23 writes that even though regarding the obligation of Birchat Hamazon it matters if a person only ate a kezayit or is full or whether they drank, if everyone is fulfilling their own obligation it isn't relevant for zimmun.
- Shulchan Aruch 193:2 writes that a third person can join two that already started eating if he is “Koveh” (establishes his place) with them. Mishna Brurah 193:21 writes that if one doesn’t eat while sitting and eat at the same table one isn’t considered as being Koveh with the others. Magen Avraham 195:2 and Mishna Brurah 197:3 also include the requirement of sitting at the same table.
- Tosfot Brachot 45a s.v. shelosha, Vezot Habracha p. 131 citing Rav Elyashiv and Rav Tzvi Weber. He also quotes Rav Sheinberg who said that if they went to wash at the same time it is like they started together.
- Mishna Brurah 193:18
- Piskei Teshuvot 193:7
- Yalkut Yosef (vol 3 pg 375), Piskei Teshuvot 193:7
- Shulchan Aruch OC 195:1, Mishna Brurah 195:6
- Rama 193:3 writes that even if three people aren’t obligated in Zimmun it’s preferable that they make Zimmun because of Berov Am Hadrat Melech, that it’s preferable to honor Hashem in multitudes. Mishna Brurah 193:23 writes that the same would apply if there are more than 3 people. However, Magen Avraham in name of many poskim that since one can’t fulfill the Birkat HaMazon for another person one is also not allowed to make a zimmun together. Mishna Brurah 193:24 concludes that the Magen Avraham is more logical. Vezot Habracha p. 134 concurs.
- Rav Shlomo Zalman Auerbach (Minchat Shlomo Brachot 45a cited by Dirshu 193:22)
- Rava Tosfa in Gemara Brachot 50a states that if three people ate together and one said birkat hamazon then the other two can afterwards include him in the zimmun, even though he doesn't fulfill his obligation, they fulfill their obligation. Rambam Brachot 5:14, Rosh Brachot 7:28, and Shulchan Aruch 194:1 codify this as the halacha.
- Rav Hai Goan (cited by Rashba 50a s.v iy nami) understood Rava on 50a to mean that if there were three groups of three people who ate bread together and one from each group joined together for a zimmun the others would be exempted from a zimmun. The reason is that since the original groups only had three people once one of them answered a zimmun he is discounted from their group and as such they can't make a zimmun anymore. The Rashba explains that according to Rav Hai Gaon only if the other person answered a zimmun is he disqualified from joining their group, but if he forgot and say birkat hamazon without a zimun he wouldn't invalidate his group's zimmun and he can join their zimmun although he isn't going to fulfill his obligation. Rama 194:1 holds like Rav Hai Goan. Bet Yosef 193:6 cites it.
- Furthermore, the opinion of Rashi 50b s.v. vlo, Tosfot 50a s.v. aval, and Rambam Brachot 5:11 explain the gemara Brachot 50a to mean that if a person answered a zimmun and then joined another group he can't answer another zimmun.
- The Rosh Brachot 7:28 writes that if two of them already said birkat hamazon there's no more obligation of zimmun for any of them. He infers it from the gemara that says only if one already said Birkat Hamazon implying if it was more then there would be no obligation of zimmun anymore. Rashba Brachot 50a s.v. inhu and Hagahot Maimoniyot 5:30 agree. Maamer Mordechai 194:3 and Keysad Mezamnin 194:5 p. 112 codify this.
- Maamer Mordechai 194:3 explains that although the Rashba explains that one can only create a zimmun if a majority of the original group is there, since two need to say birkat hamazon they would have a zimmun even if only one of those who already said birkat hamazon would join them. Biur Halacha 194:1 s.v. echad agrees.
- Mishna Brurah 197:20 writes that if one out of three people ate a Kezayit of a food (other than bread) or drank a reviyat of drinks (other than water), the three people can still make Zimmun.
- Eliya Rabba has a doubt about the case where two ate bread with someone who ate a kezayit of another food and one who ate bread said birkat hamazon if they can still have a zimmun. Perhaps since majority of the group still didn't say a bracha achrona they can have a zimmun or perhaps since only the one who had bread and still didn't say birkat hamazon needs a zimmun the obligation of the zimmun disappeared. He concludes that the latter approach is more reasonable. Birkei Yosef (Shiurei Bracha 194:1), Maamar Mordechai 194:3, Magen Giborim (Elef Hamagen 194:1), and Biur Halacha 194:1 s.v. echad agree. Maamer Mordechai elaborates that according to the Rosh the one who already said birkat hamazon is like someone who ate a kezayit of another food so if the other two ate bread that would create a zimmun. But according to the Rambam that someone who ate a kezayit of another food can't join for a zimmun of three the one who already said birkat hamazon is better than someone who ate a kezayit but either way in this case there's no zimmun.
- Magen Avraham 197:4 quotes the Aguda who writes that if one who didn't eat bread forgot and made a bracha achrona he is no longer included in the zimmun at all and it is unlike someone who ate bread and then forgot and recited birkat hamazon. Maamar Mordechai 194:3 and Mishna Brurah 197:9 agree.
- Bet Yosef 193:1 s.v. vchen holds that someone who already said zimmun can join a zimmun of three but not a zimmun of ten. Birkei Yosef 194:1 agrees. Keysad Mezamnin p. 118 explains that a zimmun of ten requires a greater level of establishment to create a zimmun than a zimmun of three (Brachot 45b) and therefore someone who already said birkat hamazon can't join. However, the Eliya Rabba 194:1 argues. Biur Halacha 194:1 s.v. echad agrees.
- Rav Hai Goan's understanding of Brachot 50a, Rashba 50a s.v. iy nami, Rama 193:6
- Rashba Brachot 50a s.v. iy nami, Rama 193:6
- Rosh Brachot 7:29 quotes Rabbenu Yehuda who explains that the gemara meant that if the original groups did zimmun the ones who left lost their obligation of zimmun. Even though the Rosh argues with Rabbenu Yehuda, Rabbenu Yonah 36a s.v gemara and Raavad Brachot 5:11 agree with Rabbenu Yehuda. Rashba 50a s.v. iy nami implies that he agrees. Shulchan Aruch OC 193:6 codifies the opinion of Rabbenu Yehuda.
- Gemara Brachot 45b, Shulchan Aruch OC 194:2, Mishna Brurah 194:8
- Shulchan Aruch 192:1
- The Kol Bo 25 cited by Bet Yosef has a doubt whether those joining have to eat a kezayit or reviyit of drink to join or anything is sufficient. Shulchan Aruch rules that a kezayit of food or reviyit of drink is necessary.
- Shulchan Aruch 197:2. Rav is quoted in Gemara Brachot 48a as saying that if one of the ten ate a vegetable he can join for a zimmun. Tosfot s.v. tisha adds that even drinking counts like eating. Rambam Brachot 5:8, Tur and Shulchan Aruch 197:2 codify this gemara.
- Rabbi Zeira asked whether two or three people who ate a vegetable can join and Rav Yehuda told him that they could. Rabbi Zeira didn't ask whether four who ate vegetables can join because he thought that you need a significant majority. Rabbi Yirmiya argued that four could join which there is still a majority of those who had bread. Rashi understands that Rabbi Zeira didn't ask original because of his idea but really he regretted that he didn't ask about four. The Bet Yosef 197:2 explains for the Rambam and others that Rabbi Zeira was steadfast in his opinion that four can't join. Interestingly, the Or Zaruah 1:197 cited by Bet Yosef in fact holds that four can join. Shulchan Aruch doesn't hold like the Or Zaruah.
- Halacha Brurah 192:12
- Sh"t Bear Moshe 1:2 compares standing for Elokenu of zimmun to standing for barchu and concludes that one should stand but if one doesn't there is what to rely upon. Rav Schachter (Brachot Shiur 87 at the end) said that Rav Soloveitchik's minhag was not to stand for Elokenu of zimmun of ten but those who do stand think that it is like a dvar shebekedusha (Kesef Mishna Brachot 5:7).
- Is Zimmun a Dvar Shebekedusha? The Rambam Brachot 5:7 writes that even though women can have a zimun on their own they can’t have a zimun of ten with Elokenu. (Interestingly, the Sefer Meorot Brachot 45a argues on the Rambam.) Kesef Mishna Brachot 5:7 explains that a zimun with Elokenu is a dvar shebekedusha. Meiri Brachot 47b s.v. nashim, Bach 199:7, Perisha 199:16, Ateret Tzvi 199:5, and Mishna Brurah 199:15 agree with this statement explicitly. However, Even Haazel Brachot 5:7 and Divrei Yirmiyahu Brachot 5:7 argue that zimun with Elokenu really isn’t a dvar shebekedusha but requires a minyan for the respect of Hashem’s name (Brachot 45b) and that’s why a child can join for zimun. (See Meiri who tries to address this.) Kavod Yom Tov Brachot 5:7 provides a compromise calling it a minor dvar shebekedusha.
- S”A 193:1
- Rama 193:2, Mishna Brurah 193:11
- Mishna Brurah 193:19
- The Gemara Brachot discusses whether two people can create a zimmun. Rabbi Yochanan holds that two people can't have a zimmun but Rav holds they can. The Rif 33a, Rosh Brachot 7:6, Or Zaruah Brachot n. 184, and Rambam Brachot 5:16 hold like Rabbi Yochanan. Shulchan Aruch 193:1 codifies the opinion of Rabbi Yochanan.
- Gemara 45b establishes that if someone doesn't know how to say birkat hamazon he can fulfill his obligation by listening to someone who does know how to say birkat hamazon. Rif 33a, Rosh 6:7, Rambam Brachot 5:15, and Shulchan Aruch 193:1 quote this as the halacha.
- Tosfot Brachot 45b s.v. shani concludes that if a person doesn't understand the birkat hamazon he can't fulfill his obligation with a zimmun. Mordechai, Or Zaruah Brachot n. 186, Rabbenu Yonah Brachot 33a s.v. vnira, and Rosh Brachot 7:6 agree. However, the Rosh cites Rashi who held that even if those listening don't understand they can fulfill their obligation by listening to birkat hamazon in Hebrew as we find by Megillah 17a. Tur and Shulchan Aruch 193:1 hold like the Tosfot. Darkei Moshe 193:1 writes that the minhag is to rely on Rashi. Magen Avraham 193:2 and Mishna Brurah 193:5 accept the Darkei Moshe.
- The Birkat Avraham 9:287 (cited by Olot Tamid 193:2) writes that even Shulchan Aruch would accept that for a zimmun of three it is possible to fulfill the obligation of someone who doesn't understand Hebrew and it is only an issue if there's only two people. However, the Olot Tamid argues that Shulchan Aruch doesn't distinguish. (Tosfot Brachot 45b s.v. shani explicitly is against the Birkat Avraham.) Biur Halacha 193:1 s.v. eino cites the Birkat Avraham.
- Rif Brachot 35b holds that someone who ate something besides bread can be counted for a zimmun of ten and not for a zimmun of three. Rambam Brachot 5:8, Rashba Brachot 48a s.v. ulinyan, and Sar Mkusi (Tosfot Brachot 48a s.v. tisha) agree. However, the Ri (Tosfot Brachot 48a s.v. tisha), Rabbenu Yonah 35b s.v. vafilu, and Rosh Brachot 7:21 argue that there’s no distinction between a zimun of three and ten and one person who ate something besides bread can join a zimun of three.
- According to Tosfot unlike Rif and Rambam, what do you need to eat? Tosfot 48a s.v. tisha says that anything including a drink is sufficient. Bet Yosef 197:3 cites the Kol Bo 25 who says that you can only join a zimmun of three if you ate mezonot.
- Shulchan Aruch O.C. 197:3 writes that there are three opinions as to whether two who ate bread may join in a zimmun with a third person who didn't eat bread. The first opinion holds that one may not join together for a three person zimmun unless all three people ate bread. The second opinion holds that they may join together as long as the third person ate mezonot. The last opinion holds that as long as the third person ate anything, they may join together for a zimmun. Shulchan Aruch writes that in order to avoid a dispute one should not allow a third person who doesn't want to eat bread to join with the first two who are eating bread. The Mishna Brurah 197:22, however, writes that the minhag is in accordance with the last opinion allowing a zimmun of three as long as the third person ate something. Halacha Brurah 197:12 also writes that some are lenient. Chacham Ovadia Yosef in Sh"t Yechave Daat 4:13 (in the footnote) quotes the Knesset HaGedola who says that the minhag is to allow a zimmun of three as long as the third person ate something. He explains that the only reason Shulchan Aruch said one should avoid such a zimmun is because in his day people used to listen to the birkat hamazon of the leader of the zimmun, however, nowadays since everyone says the birkat hamazon to themselves such a zimmun is allowed. Mishna Brurah 197:20 notes that the third person must eat at least a kezayit in order to obligate a bracha achrona. Kitzur Shulchan Aruch 45:10, Shulchan Aruch 196:3, and Ben Ish Chai (Korach n. 5) say that ideally the third person joining two others who ate bread for a zimmun should have at least a kazayit of mezonot or wine but it is permissible to join as long as he had a kazayit of any other fruit, vegetable, or drink besides water. Rabbi Mansour discussed this topic on several occasions. One time ("Can Three People Make a Zimun if One of Them Did Not Eat Bread?" on 11/24/11) he followed the Shulchan Aruch and Rav Moshe Halevi. However, in two later discussions ("What Must the Third Person Eat for Three People to Make a Zimun?" on 5/19/13 and "Must All Three People Have Eaten Bread in Order to Recite a Zimun?" on 7/9/19) he followed Rav Ovadia Yosef.
- Beiur Halacha 194:1 s.v. Echad cites the Eliyah Rabba who has a safek about this and concludes that there is no obligation for Zimmin. He quotes the Maamar Mordechai, Birkei Yosef, and Magen Giborim as agreeing. Sefer Keysad Mezamnin (9:22, p. 123) concurs.
- Chaye Adam 48:1 writes that if two people eat bread together and a third person ate a kezayit of another food, if the one who ate the other food said a Bracha Achrona without Zimmun, there is no obligation of Zimmun since the one who ate food other than bread had a non-permanent meal to begin with and has already made a bracha achrona. Sefer Keysad Mezamnin (9:20, p. 122) concurs.
- Shulchan Aruch O.C. 199:6, Kitzur Shulchan Aruch 45:22
- Shulchan Aruch O.C. 199:7
- Rama 199:10, Kitzur Shulchan Aruch 45:22
Counting a Kattan in General
The Gemara (Berachot 47b-48a) has a series of statements about being able to make a zimmun with two people and a Sefer Torah, Shabbat, or just by virtue of the fact that they're both Talmidei Chachamim who can speak in Halacha. Then, the Gemara quotes R' Yochanan that one can make a zimmun with a Kattan Poreach, and then it brings a Baraita to support that. Afterwards, the Gemara says the Halacha does not follow any of the above statements rather, the Halacha follows Rav Nachman that a Kattan who knows to whom we pray may be counted towards a zimmun. The Gemara continues to bring a story about how Rabbah asked young Abaye and Rava whom we recite Birkat Hamazon to and how they answered correctly.
- There are three basic approaches in the Rishonim as to how to read the Gemara, resulting in the following opinions regarding whom we count for a zimmun.
- The Rif (Berachot 35a) quotes Rav Hai Gaon who holds one may count any Kattan who knows whom we say Birkat Hamazon to, even from nine or ten years old. Rambam (Bracha 5:7) and Rabbenu Yonah (Brachot 35a s.v. aval) agree. He mentions that a child can be counted from eight or nine years old.
- Rabbeinu Chananel (quoted by Rabbenu Yonah) is of the opinion that a twelve year old, similar to a concept we find by Nedarim (Mufla Samuch LaIsh), may be counted for a Minyan, if he knows to whom we recite Birkat Hamazon. Ramban (Chidushim Brachot 48a) rejects this opinion saying that it is without proof.
- The Rosh (Berachot 7:20) is strict for a Yerushalmi that one may never count anyone below the age of thirteen for a Minyan. Tosfot 48a s.v. leyt agrees. The Beit Yosef (199:10) adds that the Hagahot Maimoniot (Berachot 5:6), Samag (Aseh 27), and Maharik (Shoresh 49) also hold like the Rosh, and Rabbeinu Yonah testifies that many of his contemporary Chachamim acted that way.
- The Raavad (as quoted by Ramban Chidushim Brachot 48a, see Raavad on Rif Brachot 35b) argues that a child can join for a zimmun of ten and not three. Tur 199:10 quotes Rabbenu Peretz and Rav Hai Goan who make such a distinction. Ramban (Milchamot 35b and Chidushim 48a) argues that there's no difference. Also, the Rambam Brachot 5:7 explicitly writes that there's no distinction. Shulchan Aruch 199:10 rules like the Rambam. How many children can join for a zimun of ten? The Bet Yosef 199:10 cites the Kol Bo (ch. 25) who says that we can even have 3 children. The Baal Hameor Brachot 35b holds that you can join even 4 children for a zimun. The Ramban Milchamot 35b argues only one. Also, the Shiltei HaGiborim Brachot 35a n. 5 citing the Riaz says only one child can join. Magen Avraham 199:6 and Birkei Yosef 199:3 hold like the Riaz to only join one child for a zimun of ten.
- In the end, Shulchan Aruch OC 199:10, rules like the Rif and Rambam against the Rosh. Rabbenu Yonah Brachot 35b s.v. aval writes that a child can join for a zimmun but not for a minyan since for zimmun each person can fulfill their own obligation of Birkat Hamazon, however, for minyan the Dvar Shebekedusha is something that only a congregation can say and not an individual. Magen Avraham 199:6 agrees. The Darkei Moshe 199:4 says their Minhag is like the Rosh. (See Yabia Omer OC 4:9:2-3 and OC 1:42:4 regarding the distinction between using a Kattan for zimmun and not for Tefillah).
A Lower Age Limit
The Bet Yosef (199:10) discusses according to those who include a child whether there is a specific age limit. The Rif 35a mentions the child has to be nine or ten, Rabbenu Yonah 35a s.v. katan quotes the Rif as holding eight or nine, and Rambam Brachot 5:7 says seven or eight. The Bet Yosef writes that it seems that these ages aren't specific as long as they really know who they are saying Birkat Hamazon to. However, he cites the Rashba (Berachot 48a s.v. vleyt) and Rivash (Siman 451) both hold that the child needs to be a certain age of Chinuch and not just that he knows to whom he is saying Birkat Hamazon. Shulchan Aruch 199:10 writes that we include a child for zimmun and it isn't clear from what age. Gra on 199:10 assumes that he follows the Rivash.
The Magen Avraham 199:6 writes nine or ten. Birkei Yosef 199:4 writes that even though it seems Shulchan Aruch really a child can be counted even as old as six years old, we should be strict for the Magen Avraham since many opinions don't like like the Rif in the first place and it is possible that he himself would only say it from nine years old specifically. In Shiurei Beracha (199:2) he found the Sefer HaOrah of Rashi ch. 44 who also says from the age of nine or ten. The footnotes of Peat David points out that this quote is from the Rif but certainly wasn't authored by Rashi. Machatzit HaShekel 199:6 agrees with Chida.
The Maamar Mordechai (199:4) broadens the discussion about this comment of the Magen Avraham. Every child reaches chinuch at a different age, so the Magen Avraham was just picking one and intended for us to be Somech on what it says in Beit Yosef. He disagrees with the Chidah's reading of the Magen Avraham and thinks that it's Lefaresh and not Lachalok, and he finishes by pointing to 284:4.
The Kaf HaChaim (199:29) and Piskei Teshuvot (199:5) are Machmir for the Chidah.
In Yabia Omer (2:OC:13:11), regarding the how old a child must be for one to answer Amen to his Beracha, Rav Ovadia says that the Chidah strayed from the Kav and there's no need to be Machmir as there's no Beracha Levatala. Therefore, he paskens from six. Elsewhere (OC 8:25:8) he adds a Rov that Chareidi kids know whom they're mevarech to and that one can use a Safek Sefeka if he's not sure if the kid is six.
The Ben Ish Chai (Shanah Rishonah Korach 11) says from age nine, but Rav Ovadia (Yabia Omer 9:OC 91:8:3) says Lo Dak (as is Mashma from his Lashon about Maran and the Minhag of Baghdad following Maran), unlike the Kaf HaChaim (199:29) who took it literally. It seems to be Bedaat Maran, so it would depend how you read the Magen Avraham, (like the Chidah or the Maamar Mordechai). Either way, the Ben Ish Chai recommends finding a Gadol if possible.
The Ohr Letzion (2:13:11) distinguishes between a zimmun of three and one of ten. For the former, six years old is sufficient, but one should be machmir for a zimmun bashem for nine years. Rav David Yosef (Halacha Berurah 199:13) disagrees on behalf of his father, though there is no Hasaga in Rav Ovadia's Hearot on the volume (9:108).
Vezot HaBeracha (pg 132) paskens like Chacham Ben Tzion, and Rav Mordechai Eliyahu comments that he disagrees and even allows for zimmun of ten from age six. The latter emphasizes that each Kattan Lifum Chorfeh, everybody reaches that point of understanding at a different age. The fact that Rav Mordechai Eliyahu holds from age six may be a good indication that he read the Ben Ish Chai like Rav Ovadia.
The Birkat Hashem (2:6:25) is also lenient from age six for both 3 and 10, and in footnote 90, he gives three explanations for why we should not follow the Birkei Yosef's Chumra. Firstly, the Chidah might not have meant it LeHoraah, but rather for Yechidim, as he described in Choshen Mishpat 25:6. Next, it's just not Muchrach, and, lastly, had he seen the other Rishonim and understood the Rif, he would have been Chozer Bo.
See further in Yechaveh Daat 4:13 and Yitzchak Yeranen 5:11.
- The Tur (199:10) quotes a dispute between the Rambam (5:7), who says he can be Mitztaref for both a regular zimmun and a zimmun baShem, and R' Peretz, who holds that it's only for a zimmun of ten. The Beit Yosef adds that the latter is also the opinion of Rav Hai Gaon, Tosafot (48a DH veleit), and the Mordechai (Berachot 172) quoting Rabbeinu Tam. He explains that they holds such because we're more strict about zimmun of three than a zimmun of ten, however, the Mordechai records that the Rabbeinu Tam didn't want to rely on his opinion in practice. The Orchot Chaim (39) quotes the Raavad (Temim Deim n. 1) as also holding this way because we go out of our way to enable making a zimmun of ten to praise Hashem with His name but a zimmun of three is insufficient reason to for us to accept the minor. The Shulchan Aruch (199:10) paskens like the Rambam.
- The Kaf HaChaim (199:31) quotes Poskim who say that a Kattan may not, however, count towards a Minyan or Panim Chaddashot for Sheva Berachot. This is also the ruling of Rav Mordechai Eliyahu (in his comments to Vezot HaBeracha pg. 132). See also Yalkut Yosef.
- The Birkat Hashem (vol. 2 ch. 6:25 fn. 90) says that to join a zimmun of three, he has to eat bread or Mezonot, not just a vegetable based on a Safek Sefeka. Although, for ten, even a vegetable is sufficient.
- Rav Yosef Karo (Beit Yosef 199:10) quotes the Kol Bo (Siman 25) that there must always be a Rov Nikar of Gedolim, so a regular zimmun can have a maximum of one Kattan and a zimmun of ten can have up to three.
- The Mishnah Brurah 199:25 quotes the Magen Avraham (199:6) quoting the Shiltei HaGibborim (Berachot 35 1:5) that only one Kattan may be counted. In the Shaar HaTziun (199:14) he says the Magen Avraham and Birkei Yosef both say this bedaat Maran. Upon reading the Birkei Yosef (199:3), it's clear that the Chidah felt Maran actually holds like the Kol Bo, who allows one to use many Ketanim as long as there's a Rov Nikar of Gedolim. Rather, the Birkei Yosef was being Machmir for the Riaz, because many poskim sound that way. This really isn't a Shaylah for Ashkenazim.
- The Kaf HaChaim (199:30), Birkat Hashem (vol. 2 ch. 6:25), Halacha Berurah (199:13), Yalkut Yosef 199:4 (199:6 in Kitzur Shulchan Aruch), and Piskei Teshuvot (199:5) all hold say one may only use one Kattan regardless. The Birkat Hashem quotes many Sephardi Poskim, such as the Birkei Yosef, Erech HaShulchan (199:2), Kaf HaChaim ibid, Siddur Beit Menuchah, Chessed LeAlaphim, and Yechaved Daat 4:13.
- VeZot HaBeracha (pg. 132) quotes the ruling of R' Chaim Pinchas Sheinberg and Rav Mordechai Eliyahu that if a Sephardi, Ashkenazi, and Kattan eat together, they may make a zimmun and the Sephardi should be Mezamen. Moreover, Rav Shlomo Zalman Auerbach holds that if they're eight Sephardim, an Askenazi, and a Kattan, one of the Sephardim should make a zimmun BaShem, but the Ashkenazi should answer quietly without the Shem. This is also the ruling of the Piskei Teshuvot (199:5) and it's quoted in Yalkut Yosef (Heb-Eng) there.
- The Perishah had a Girsa in the Tur that ketanim could make their own zimmun, but the Kaf HaChaim (199:18) points out from Maamar Mordechai (199:2) and Yafeh LeLev (199:2) that the Turim printed from the times of Maran and the Bach did not have that Girsa. Neither did the Rambam or Shulchan Aruch themselves. Rav David Yosef (Halacha Berurah 199:14) says that three ketanim who eat together should not make their own zimmun.
- The Piskei Teshuvot (199:5) says that they should answer as appropriate to other people's zimmun based on Chinuch if they ate together with those making a zimmun.
- The Kaf HaChaim (199:21) sounds like they have to be three Gedolot. The Hebrew-English Yalkut Yosef in the footnotes quotes a Maayan Omer (pg 305) that says it's permissible.
- Mishna Brurah (Beiur Halacha 197 s.v. Imahem) quotes the Pri Megadim and Chaye Adam who write that if there’s a safek by zimmun one should say it however by the Zimmun of ten people one shouldn’t say it because it includes Hashem’s name.
- Gemara Brachot 45b, Shulchan Aruch OC 200:1
- Tosfot Brachot 46a s.v. ad understands that the gemara is discussing when you listen to a zimmun and plan to eat again how much of birkat hamazon do you need to listen to and he says we hold like Rav Sheshet that you need to listen until Hazan Et Hakol. However, the Rosh Brachot 7:12 cites Tosfot and then cites the Rif who follows Rav Nachman who says zimun ends at baruch she'achalnu. Shulchan Aruch 200:2 rule like Rav Nachman and Rama like Rav Sheshet.
- Gemara Brachot 45b records the story with Rav Papa and someone else stopped their meal for one other, which the Gemara says isn't necessary but is considered going beyond the letter of the law. Shulchan Aruch 200:1 codifies this.
- Vezot HaBracha (pg 128, chapter 14) quotes that Panim Meirot that the original establishment was that one person say it aloud and everyone listen. However, S”A 183:7 writes that the practice that should be followed nowadays is that one person say it aloud and everyone to follow along Bracha by Bracha.
- S”A and Rama 183:7, Vezot HaBracha (pg 128, chapter 14)
- S”A and Rama 200:1 identify clearly the crucial part of Zimmun, according to S”A it is the Zimmun of Baruch SheAchalnu and according to the Rama it is including the first Bracha. Mishna Brurah 183:28 holds that Ashkenazim should at least say the first Bracha quietly together with the Mezamen and those who have the minhag that everyone just says it to themselves are mistaken. This is also the opinion of Vezot HaBracha (pg 129, chapter 14) and he warns that not doing so is against the halacha. Vezot HaBracha (pg 335) quotes Rav Wosner in Kovetz MeBet Levi (Nissan 5758) who defends the minhag slightly. Yalkut Yosef (vol 3 pg 371) says that a Sephardi who is a Mezamen for Ashkenazim should say the first Bracha out loud. Rav Schachter in Brachot Shiur 87 (min 70) said that Ashkenazim should have the mezamen say the entire birkat hamazon out loud slowly and everyone say it along with him and if they don't so they aren't fulfilling zimun.
- Mishna Brurah 193:17, Vezot HaBracha (pg 129, chapter 14) also quotes the Chazon Ish who argues but still quotes the Mishna Brurah as the primary opinion.
- Vezot HaBracha (pg 129, chapter 14)
- The Magen Avraham (Intro to 192) quotes the Zohar which says that words of kedusha require preparation and that is the basis for the minhag to invite everyone to say Birkat Hamazon. The Magen Avraham writes that the Ashkenazic minhag was to say it in Yiddish with the words "Rabbotai Mir Velin Benchin". The Mishna Brurah 192:2 adds that it may be said in Hebrew with either the phrase "Ten Lanu Kos UNivarech" (if one is saying Birkat HaMazon over a cup of wine) or "Bau UNivarech" (if one isn't saying Birkat HaMazon over a cup of wine). The Kitzur Shulchan Aruch 45:6 adds that this invitation could be said in Aramiac with the words "Hav Lan UNivarech." Rav Mordechai Eliyahu (comments to Kitzur Shulchan Aruch 45:12) writes that the Sephardic minhag is to say this invitation in Aramiac with the words "Hav Lan VeNivrich LeMalka Iylah Kiddisha."
- The Magen Avraham (Intro to 192), Mishna Brurah 192:2, and Kitzur Shulchan Aruch 45:6 records the Ashkenazic minhag to answer the invitation with the pasuk "Yehey Shem Hashem Mivorach MeAtah VeAd Olam". Rav Mordechai Eliyahu (comments to Kitzur Shulchan Aruch 45:12) writes that the Sephardic minhag is that those participating in the Birkat HaMazon answer "Shamayim," meaning, that this should be done with the permission of heaven.
- Shulchan Aruch 192:1 writes that the mezamen should begin the zimmun by saying "Nivarech She'achalnu Meshelo". Rav Mordechai Eliyahu (comments to Kitzur Shulchan Aruch 45:12) writes that the Sephardic minhag is the mezamen starts the zimmun with the words "Birshut Malka Iylah Kiddisha UBirshutchem, Nivarach She'achalnu Meshelo."
- Shulchan Aruch 192:1 writes that those participating in the zimmun should respond "Baruch She'achlnu Meshelo Ubituvo Chayinu."
- Shulchan Aruch 192:1 writes that the mezamen should conclude "Baruch She'achlnu Meshelo Ubituvo Chayinu."
- S”A 198:1, Kitzur Shulchan Aruch 45:20, Vezot HaBracha (pg 129, chapter 14)