Hilchot Nedarim

As the minutiae are great and the practicality of taking a Neder in Mishnaic Hebrew is not, it may be too confusing to attempt translating accurately into English. Hence, many specific cases and their discussions have been omitted.

Precautions and Circumstances for Taking Nedarim

General Warnings

1. One should not regularly take a Neder: even if he fulfills it, he is called a Rasha and sinner.
2. If one delays fulfilling a Neder, his account is "opened" in Heaven.
3. Taking a Neder is equivalent to building a Bamah at a time in which doing so is prohibited, and following through with it is equivalent to bringing a Korban on that Bamah. Instead, it's better he have it anulled. This is only true, however, with respect to regular Nedarim. It's actually a Mitzvah to fulfill Nidrei Hekdesh, and one should only attempt to anull them in very drastic situation.

Tzedaka

1. It's preferable to not even pledge Tzedaka in the form of a Neder. Rather, if he has the money, he should donate it right away. If he doesn't, it's better not to take the Neder until he does.
2. If one does have to pledge with the community, he should add "Bli Neder."

General Leniencies

1. One may take a Neder in a challenging, trying time ("Et Tzarah").
2. Nedarim and Shevuot may be taken as means of strengthening one's religious commitment, both in terms of fulfilling positive Mitzvot and evading the violation of negative ones.
3. However, one must be extremely careful when taking a Neder or Shevua in the context of Mitzvot, because even the more innocuous formulation will actually be binding.
4. Nedarim Siyag LePrishut: Taking a Neder to adjust one's personal attributes and tendencies is a form of serving Hashem. Examples include controlling one's extravagant appetite for meat and wine by taking a Neder against eating them for a period of time. Similarly, forbidding oneself from general indulgences is a means of bringing oneself to lesser focus on materialism. Nevertheless, one shouldn't become accustomed to taking Nidrei Issur (Prohibitive Nedarim). Instead, one should abstain from the actions and entities that he wishes to abstain from but without taking a Neder in the first place.

Formulating Nedarim

The Absence of Innumerable Specific Examples

1. There are many complicated minutia discussed in the Talmud and its commentaries regarding specific formulations of Nedarim, but they don't make it to the page of Shulchan Aruch for practical reasons.

Ikar HaNeder & Hatfasah BaDavar HaNadur

1. The essential form of a Neder entails declaring that a permitted object be prohibited and be associated with an object which itself is the product of a previous vow (Davar HaNadur). For example, "This loaf of bread should be prohibited to me like a Korban," because a Korban is an inherently permitted animal that is sanctified via a Neder.
2. Similarly, if one already prohibited an object upon himself, he can then subsequently prohibit another object by associating it with this one. For example, "This loaf of bread should be prohibited to me like that one (which he already prohibited via a Neder)."
3. The associated object need not be a Korban, but, rather, it can be anything that is sanctified with one's speech.
4. If one hears his fellow declare a Neder and then himself says "And me like you!" within Toch Kedei Dibbur, he creates a bona fide Neder. This is true even if a hundred people follow, one at a time, each within Toch Kedei Dibbur of the last.

Hatfasah baDavar HaAssur (Inherently Prohibited Objects)

1. If one associated the object with an object that is inherently prohibited, such as a non Kosher animal or idol (Hatfasah baDavar HaAssur), the Neder is not binding on a Torah level. For example, declaring that "This meat should be prohibited unto me like pig meat" is ineffective.
2. Some argue that, on a rabbinic level, any such a Neder with association to an inherently prohibited object is effective on an Am HaAretz. Additionally, basic Charatah would be insufficient, and he would instead require a Petach from a different approach (MiMakom Acher) to annul it. Many others, however, argue that this stringency by Am HaAretz only applies when his ineffective Neder is taken to prohibit his wife unto him. This opinion also claims that, nowadays, everyone has the status of Am HaAretz.
3. The Chachamim did not impose their penalty in a case in which one was forced to take a Neder against his wife, and he associated her with an inherently prohibited object.
4. Granted an individual cannot declare his wine as "Yayin Nesech" or "Pat Akum" through a standard Neder, if he did it as a penalty to others for violating a stipulation he made, some claim it's effective, while others disagree.
5. A community can take punitive measures against members who act inappropriately and prohibit the objects of such individuals on others.

Ambiguous Formulations and Stam Nedarim LeHachmir

1. If one makes an ambiguous association to an item, such that his words can be interpreted in one of two ways, either as a Davar HaNadur or as a Davar HaAssur, the axiom of "Stam Nedarim LeHachmir" dictates that we assume he meant the Davar HaNadur. Therefore, if he assoiated his Neder with Maaser, without specifying whether he meant Maaser Rishon (a Davar HaAssur) or Maaser Behemah (a Davar HaNadur), the Halacha assumes by default that he meant the latter, and his Neder is effective.
2. However, if he clarifies his intention as being the Davar HaAssur, he is believed and doesn't even need She'elah on his Neder, even if he's an Am HaAretz.
3. At the same time, if most inhabitants of the community understand the ambiguous unspecified language to refer only to the Davar HaNadur, then he is not believed if he claims that he really intended for the Davar HaAssur. As such, one who associates his Neder with Terumah, which can mean either Terumat of produce given to Kohanim, a Davar HaAssur, or Terumat HaLishkah (donations to the Beit HaMikdash), a Davar HaNadur, and doesn't specify which one he had in mind, is bound by his Neder. If he does specify in either direction, he is believed, but, if most people in his area refer to Terumat HaLishkah as Terumah, even if he claims he meant Terumah of produce, the Neder is binding and he is not believed against the local parlance. Some say that a Talmid Chacham is believed against the majority, while others distinguish between this case and other ones.
4. The gravity in deciding ambiguous references based on the majority of the community also works to be lenient against the one taking the Neder. For instance, if one associated his Neder with Yayin Nesech, which can refer to either Yayin Nesech that is brought on the Mizbeach with certain Korbanot in the Beit HaMidkash or to Yayin Nesech used in Avodah Zarah worship, it takes doesn't take effect, even if he follows up by claiming he had the former in mind.

Unintuitive Elucidations of One's Formulation (Perusham LeHakel)

1. One who takes a Neder that intuitively would be interpreted one way ("I prohibit myself from my wife" intuitively means the woman he's currently married to) but then follows up and elaborates that he actually intended to refer to something that is a valid interpretation of his words but completely unintuitive given a lack of context ("I meant my first wife whom I already divorced.") is believed if he's a Talmid Chacham, but not if he's an Am HaAretz, in order to prevent making light of Nedarim. Although, an Am HaAretz would only require Charatah and not a Petach.
2. If an Am HaAretz did this and subsequently violated his Neder, although we penalize one who violates a Neder MiDeoraita by making him endure a period of time without violating his Neder equal to the interval of time over which he did violate it, we do not penalize him in this situation, since it is only a Neder MiDerabbanan.
3. For Ashkenazim nowadays, everyone has the status of Am HaAretz.

Yadot Nedarim

1. An incompletely formulated Neder, otherwise known as a Yad, can take effect just as a regular Neder does or it can not, depending on the level of ambiguity. If one's intention is mostly apparent (ידים מוכיחות), it is a valid Neder. That is to say, that if one says "I vow from you that I won't eat from you," (מודרני ממך שאיני אוכל לך) without saying "prohibited" or "Korban," it is nevertheless valid.
2. If the formulation is further lacking (ידים שאינן מוכיחות), i.e. it can be interpreted in more than one way, then some hold that we default to the most apparent interpretation, while others say the entire Neder is invalid.
3. If the formulation lacks any implication of a neder altogether, such as saying "That I won't ) it is not valid .
4. "I vow to you from eating and benefiting." (מודרני לך מאכילה או מהנאה) creates a Neder prohibiting eating and benefiting both ways between the one who took the vow and the one to whom he said it.
5. "I vow from you from eating and benefiting." (מודרני ממך...) only creates a one way prohibition on the one who took the vow receiving benefit from the one he said it to.
6. Due to the fact that wicked people are more oft to take Nedarim, one who takes a Neder "Like the vows of the wicked, this should be assur to me," (נדרי רשעים) it would be effective. Inversely, Tzaddikim never take Nedarim, so a Neder formulated on "Like the vows of Tzaddikim" (כנדרי צדיקים), would not be effective. However, Tzaddikim do volunteer Mitzvot, so a Neder formulated on "Nidvot Tzaddikim" (נדבות צדיקים), would be effective.

Neder Formulated as a Shevua

1. A Neder fundamentally differs from a Shevua in that a Neder is a prohibition that takes effect on the item vowed upon, while a Shevua takes effect on the person. As such, the subject of a Neder must be the item at hand ("This item should be prohibited to me"), and the subject of a Shevua must be the person ("It should be prohibited for me to do this action"). If a Neder is formulated in the language of a Shevua, there's is a great debate if it takes effect at all or at least on the level of a Yad, and many opine that it is ineffective, unless it's with respect to performing a Mitzvah. Nevertheless, because it has become commonplace to take Nedarim in such a language, one should not be lenient, lest people become even more lax with Nedarim.
2. Some argue that Nezirut is outside the scope of this discussion and would take effect regardless, while others disagree.

Kinui Nedarim

1. The Torah's mandate enabling one to take upon himself a Neder, Korban, Shevua, or Nezirut is not limited to the perfect pronunciation of the keywords (Neder, Korban, Shevua, and Nazir). Even a mispronunciation would take effect, given it's common to pronounce the word that way by some people in the place one is taking the Neder. For example, "Konam" could legitimately substitute for "Korban" in the time and communities of the Talmud. Gross mispronunciations (Kinuiyei Kinuiyim), however, are not effective.
2. The effectiveness of usage of the above keywords also depends on one's own understanding of them. If he doesn't understand what he's saying, his statement is invalid.

Items Subject to Prohibition via Nedarim

1. One can declare a Neder on an item that is not yet in existence (Davar SheLo Ba LaOlam) to be prohibited once it comes into existence.

Miscellaneous

1. If one forgot if he took a Neder or if he took a Shevuah, he must act under the stringencies of both Nedarim and Shevuot. Similarly, if he isn't sure if he took a Shevuah in the first place, he must be stringent due to the uncertainty.

See also

• Hatarat Nedarim
• Hafarat Nedarim