Mishna Berura 193:1b Three Who Eat Together (& Two Searching for a Third)

(א) אם מצטרפין לזימון אם לאו. ובו ו סעיפים:

אבל שלשה שאכלו אינ' רשאים ליחלק.1

ושנים שאכלו מצוה שיחזרו אחר שלישי שיצטרף עמהם לזימון. 2

When three people eat together they may not separate and when two people eat together it is a mitzvah for them to search for a third to join their zimun. When four or five people eat together they may not separate since they are all obligated to make a zimuun. When the group is comprised of six they may separate since each group will make its own zimun and this is true until the group reaches ten. Once the group contains between ten and twenty people they may not separate until there are twenty since they will mention Hashem’s Name

1

Once three people eat together, there is a chiyuv zimmun, so they cannot break apart because that would cause the zimmun to be dissolved.

(ו) (ו) אינם רשאין ליחלק - דכבר נתחייבו בזימון משאכלו ביחד...

תִּסְתַּיֵּים, דְּרַב דְּאָמַר אִם רָצוּ לְזַמֵּן — אֵין מְזַמְּנִין. דְּאָמַר רַב דִּימִי בַּר יוֹסֵף אָמַר רַב: שְׁלֹשָׁה שֶׁאָכְלוּ כְּאַחַת וְיָצָא אֶחָד מֵהֶם לַשּׁוּק — קוֹרְאִין לוֹ וּמְזַמְּנִין עָלָיו. טַעְמָא דְּקוֹרְאִין לוֹ, הָא לֹא קוֹרְאִין לוֹ — לָא! שָׁאנֵי הָתָם דְּאִקְּבַעוּ לְהוּ בְּחוֹבָה מֵעִיקָּרָא.

In the dispute between Rav and Rabbi Yoḥanan, it is unclear which amora held which opinion. The Gemara seeks to resolve this: Conclude that Rav is the one who said: If they wanted to join together, they may not form a zimmun. As Rav Dimi bar Yosef said that Rav said: Three people who ate as one and one of them went out to the marketplace, they call him and include him in the zimmun. The reason is because they call him; by inference, if they do not call him, no, they cannot form a zimmun. The Gemara rejects this proof: It is different there, in the case of three who ate together and one of them left, because from the outset, they established themselves as a group of three who were obligated to form a zimmun. That is why they need to call him and include him in their zimmun.

In the realm of shared meals among friends, Mishna Berura illuminates that the obligation to perform a zimmun emerges only when three individuals partake in a bread meal together.

In this communal dining experience, all participants bear the responsibility of ensuring that a zimmun takes place upon concluding the meal.

However, this obligation is confined to the realm of bread meals. Should a gathering involve three or more people enjoying cake or fruits, even those encompassing the shivas haminim—wheat, barley, grape, fig, pomegranates, olive (oil), and date—there exists no mandate for a zimmun.

(א) מי שיצא (אם) מוציא אחרים. ובו ג סעיפים:
על כל פירות ושאר דברים חוץ מפת ויין אם היו האוכלים שנים או יותר אחד פוטר את חבירו... והא דאמרינן דאחד מברך לכולם בשאר דברים חוץ מן הפת ה"מ בברכה ראשונה אבל בברכה אחרונה צריכין ליחלק וכל אחד מברך לעצמו דאין זימון לפירות:

Due to the varying opinions among Poskim regarding the obligation of a zimmun when consuming fruits of the seven species, Bach advises caution when partaking in such foods in a group of more than three individuals. He expresses concern about the possibility of a chiyuv zimmun arising and suggests avoiding situations that might lead to uncertainty regarding the obligation to perform a zimmun.

(א) ואם המסובין שלשה וכו' כתב המרדכי רפ"ג שאכלו שכתב ראבי"ה משם רבינו האי דג' שאכלו מז' מינים חייבים לזמן.

אבל הרמב"ם בפ"ה כתב דאין מזמנין אלא על הפת לבדו.

**ועל כן צריך ליזהר שלא יעשו שלשה קביעות על אחד מז' המינים לאפוקי נפשין מפלוגתא דרבוותא:**

On the other hand, Birkei Yosef takes a more lenient stance, not pressing the issue. He allows individuals to freely enjoy foods of that nature without the apprehension of a zimmun obligation. So, if you're invited for some birthday cake, go ahead and indulge without the weight of zimmun concerns, according to Birkei Yosef's perspective.

2

In our exploration of the distinctive dynamics of a meal shared by two individuals and the transformative impact when a third person joins, we can come to appreciate the next halacha of the Shulchan Aruch.

If two people are dining together and have the possibility of inviting a third person solely for the purpose of facilitating a zimmun, it is considered a mitzvah to seize that opportunity. This underscores the significance placed on enhancing the spiritual dimension of a shared meal, bringing added honor to Hashem through the zimmun.

תָּא שְׁמַע: הַשַּׁמָּשׁ שֶׁהָיָה מְשַׁמֵּשׁ עַל הַשְּׁנַיִם — הֲרֵי זֶה אוֹכֵל עִמָּהֶם, אַף עַל פִּי שֶׁלֹּא נָתְנוּ לוֹ רְשׁוּת. הָיָה מְשַׁמֵּשׁ עַל הַשְּׁלֹשָׁה — הֲרֵי זֶה אֵינוֹ אוֹכֵל עִמָּהֶם, אֶלָּא אִם כֵּן נָתְנוּ לוֹ רְשׁוּת!
The Gemara cites an additional proof. Come and hear, based on what was taught in a baraita: A waiter who was serving two people eats with them, although they did not give him permission to do so, because he will thereby be eligible to join them in a zimmun. If a waiter was serving three people, he may not eat with them unless they gave him permission to do so. Evidently, two may not form a zimmun. If that were the case, the waiter would require permission even when serving two people.

ת"ר השמש שעומד על שנים אוכל עמהם אע"פ שלא נתנו לו רשות. עומד על שלשה אינו אוכל עמהם אא"כ נתנו לו רשות מכאן משמע שמצוה לחזר אחר שלשה כל מה שיכולין משום ברכת זימון דברוב עם הדרת מלך וכן משמע נמי בפ' כל הבשר (חולין דף קו.) דאמר רבה בר בר חנה הוה קאימנא קמיה דר' אמי ור' אסי אייתי לקמייהו כלכלה דפרי ואכלו ולא יהבו לי וקאמר ש"מ אין מזמנין על הפירות דאי מזמנים על הפירות היו נותנין לו כדי שיברכו בשלשה:

The Gemara, as pointed out by the Rosh, shows us that the mitzvah of zimmun is so significant that it goes beyond just inviting friends – it even extends to recruiting waiters!

Yes, you heard it right, even the waitstaff might get an invitation to the zimmun.

Imagine the waiter's surprise when they become an honorary member of the zimmun. It just goes to show how important zimmun is; because when it comes to honoring Hashem, the more, the merrier – even if they're in uniform!