The Definition of “Eating Together” for a Zimun
Question: What is the halachic definition of three (or ten) people “eating together” to be obligated in zimun?
Discussion: To be obligated in zimun the people who are eating must be eating their meal “together,” meaning, as part of a group, as opposed to a situation where one having a meal happens to do so at the same time as others who are also present and eating their meal. This is called a kevi’us, eating as part of a fixed setting with other people. A kevi’us is usually achieved by people eating together at the same table. People who are clearly eating together even when sitting at different tables, for example the head of a household eating together with his family, are also considered to be within the setting of a kevi’us.268
People eating at the same table are considered to be eating “together” even when each person is eating their own food,269 and are merely sharing the table out of a lack of space.270 If however, they turn away from one another271 or sit at opposite ends of the table,272 they are not considered as eating within a kevi’us.
People eating together are considered as having had a kevi’us when they either began eating at the same time, or finished their meal together.273 In a scenario, however, where two people began a meal together and a third person subsequently joined them, any of the three who finishes before the others may bentch without zimun, for, in this case there is not a group of three people eating together either at the beginning, or the end, of the meal.274 [If, however, two of the people finished eating earlier but did not bentch until the third person finished as well, the group is now obligated in zimun, for the fact that the two could have resumed eating (see below) allows them to be considered as still being involved in the meal; all three people are thus seen as finishing their meal at the same time.275] Note, that although there is no obligation of zimun in this case, it is appropriate for the person who finished earlier to wait for the other two to finish and in this way bentch with a zimun.276
“Starting a meal together” is when the participants wash netilas yadayim at the same time,277 or actually begin to eat together,278 which includes when a third person joins two other people (or two people who join one person) who are still eating their first kezayis of bread.279
There are times when zimun is required when two people ate together (and have not yet bentched) and a third person joined them after they finished eating.280 If the people would be served more food and accept it, they are considered as still engaged in the meal. This third person is thus seen as eating together with them, thus obligating the group in zimun.281 If, however, even one of them282 is too full to eat anymore, or already washed mayim acharonim, or even announced his intention to bentch, his meal is now seen as over, and he can no longer join in zimun with one who subsequently arrives.283
The Acharonim284 disagree whether participants may bentch with a zimun in a situation when there was no kevi’us at all, and thus no obligation. Mishnah Berurah285 rules stringently; one should certainly not form a zimun of ten that mentions Hashem’s Name (Elokeinu) when there is no kevi’us.
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Note that the authorities who rule that using a microphone for zimun is non-problematic are discussing zimun as it is performed nowadays, which is that each individual bentches on his own. One discharging his obligation to bentch by listening to the leader’s recitation [of either the entire Birkas Hamazon (as was done in the times of the Gemara) or even only the first berachah] must hear the berachos recited by leader’s actual voice.
269 Mishnah Berurah ibid.
270 This appears to be the consensus of the Poskim, who do not differentiate why the people choose to sit together at the table (Vezos Haberachah 14, footnote 2). See, however, Ohr Letzion II, 13:10, with Bi’urim.
271 Da’as Torah 193, 2.
272 Mor Uketziah 193, ד"ה מצאתי כתוב.
273 Shulchan Aruch 193:2.
274 Mishnah Berurah 193:19. Although there is no obligation to do so, three people who eat together at least at one point during the meal may bentch with a zimun (R’ Chaim Kanievsky, cited in Toras Hazimun 7:11).
275 Mishnah Berurah ibid.
276 Sha’ar Hatziyun 193:17.
277 R’ Chaim Pinchas Scheinberg (cited in Vezos Haberachah 14, p. 131); Ohr Letzion II, 13:10 (Be’iurim).
278 Shulchan Aruch 193:4.
279 R’ Y. S. Elyashiv (cited in Vezos Haberachah 14, p. 131).
280 Mishnah Berurah 197:3 writes that the same would apply if one person finished eating and two people joined him at the table.
281 Shulchan Aruch 197:1, with Mishnah Berurah, notes 2-3 and Beiur Halachah, ד"ה מצרף בהדייהו.
282 Beiur Halachah ad loc., ד"ה מצו למיכל.
283 Shulchan Aruch ibid.
284 Rema (193:2) encourages that zimun be conducted even when there is no obligation. Magen Avraham, though (cited in Mishnah Berurah 24), forbids it.
285 193:24.