# Only when 3 people are together, must they recite it over a cup of wine.
# Even 3 people are not required to. <br>
The Rama adds that all opinions agree that it is preferable to do so. Mishna Brura 182:4 writes that although Shulchan Aruch doesn't show preference for any of the 3, the Maharshal and the Bach are strict that if you have 3, you must have a cup of wine. The Mishna Brura himself concludes that it is certainly preferable to do so, but one is not obligated. /ref> If you are saying birkat hamazon alone, it should not be done over a cup of wine.<ref>see previous note. Although the Tur writes that one should have a cup of wine even when reciting birkat hamazon alone, the Zohar Bamidbar 245b clarifies that there's no obligation to make a birkat hamazon over wine unless there is at least a zimmun of three. Yalkut Yosef 182:1 cites the Zohar and adds that one shouldn't do a birkat hamazon over a cup when he is saying birkat hamazon himself but if one still wants to, he shouldn't pick up the cup.</ref>
# Although there doesn't seem to be any differentiation between Shabbat and Yom Tov as opposed to a regular weekday, some people have the practice to use a cup of wine only on Shabbat and Yom Tov.<ref> see Rivevot Ephraim 1:150 who suggests that this could be that since we are not technically obligated to use a cup of wine for even with 3 people, people only really make an effort to be strict in this regard when they have more free time on Shabbat and Yom Tov. Yalkut Yosef 182: 1: in the footnote adds that it could be because we are trying to get to 100 berachot. <br>
see also [https://outorah.org/p/5702/ Rabbi Ari Zivotovsky] regarding special occasions</ref>