(Mishnah): If three people ate [bread] together, they must be Mezamen (prepare to say Birkas ha'Mazon together).

[The following count towards the three for a Zimun -] one who ate Demai (Peros of an Am ha'Aretz. It is Safek Tevel), Ma'aser Rishon from which Terumah was taken, or Ma'aser Sheni or Hekdesh that was redeemed;

A waiter who ate a k'Zayis;

And a Kusi (when Sancheriv exiled the 10 tribes, Kusim (Nochrim) settled there. Lions were eating them. They converted, but they did not observe all of the Mitzvos.) We are Mezamen on [all of these people].

One who ate Tevel, Ma'aser Rishon from which Terumah was not taken, or Ma'aser Sheni or Hekdesh that was not redeemed, or a waiter who ate less than a k'Zayis, or a Nochri, we are Mezamen on them.

(Gemara) Question: [Mishnah 4 below] says 'they may not separate (and bless individually)' and here it says 'they must be Mezamen'! (Why did the Mishnah need to teach this twice?)

Answer (Shmuel): One teaches [that they must be Mezamen if they ate together] at the beginning, and one teaches [so if they ate together] at the end.

Question: What is considered [eating together] at the beginning, and what is at the end?

Answer #1: Two Amora'im [argued about this]. One said that if they decided to eat together, this is at the beginning. If they ate a k'Zayis [together], this is at the end;

Answer #2 (the other Amora): If they ate a k'Zayis [together], this is at the beginning. If they finished [together], this is at the end. (We explained this like CHAREDIM, from R. Yonah 37a.)

(R. Aba citing Rav Huna, and R. Ze'ira citing Aba bar Yirmeyah): If three [ate together], there is an obligation [to be Mezamen]. If two [ate together], it is Reshus (optional).

R. Ze'ira said this in front of R. Yosa. [R. Yosa] said, we [in Eretz Yisrael] have only [the simple understanding of our Mishnah. If three [ate together], they are obligated [to be Mezamen! R. SHLOMO SIRILIYO - the Seifa equates a waiter who ate less than a k'Zayis to a Nochri, i.e. two others may not be Mezamen with him].

Rabanan here (in Eretz Yisrael have their understanding, and Rabanan there (in Bavel may rely on) their understanding (our Mishnah teaches that if three fixed to eat together, they must be Mezamen with three. If not, it is Reshus for two to be Mezamen).

Shmuel said that if two judged a case, their verdict is binding, but they are called a brazen Beis Din. (SEDEI YEHOSHUA - this is brought merely because Amora'im argue about whether or not two suffice, like they argue about Zimun.)

Note: Most Meforshim explain that one depends on the other. Even though presumably, the number of judges is a Torah law (it is expounded), we find below that we equate Zimun to Torah law (Mei Chatas). However, Shmuel holds that even one judge, his verdict is valid, even though there is no Zimun for one who ate alone! The coming teaching supports this - 'even if two judged, it is invalid.' This implies that Shmuel argues also about one!

R. Yochanan and Reish Lakish both said that even if two judged, their verdict is not binding.

(Rav Huna): If three ate, each by himself, and they joined, they are Mezamen.

(Rav Chisda): This is only if they came from three groups [i.e. they already had a Chiyuv to be Mezamen].

According to R. Zeira and his colleagues, this is if the three ate together.

Note: Most Meforshim say that 'R. Zeira and his colleagues' refers to his teaching above, that it is Reshus for two to be Mezamen; here he mentions three, for then, they are obligated. However, this is difficult. Why is it this opinion attributed to R. Zeira? Also Rav Huna said so, and here we comment on Rav Huna's teaching! Above, we said 'Rabanan there'! Further, perhaps R. Ze'ira accepted R. Yosa's rejection! (R. Ze'ira was initially in Bavel, and ascended to Eretz Yisrael.) Further, it is not clear why this law depends on that one. Perhaps this is why Pnei Moshe explains that R. Ze'ira accepted R. Yosa's rejection; we say that according to him, each group had three who ate together. If so, why did the Gemara not teach the law according to those who say that two is Reshus? If the law is not clear when they came from groups of two, which had Reshus to be Mezamen, the Gemara should have asked this! Further, we should attribute this opinion to R. Yosa, who explicitly said so; it is not clear whether R. Ze'ira accepted his words. I prefer to explain that our Gemara teaches the opinion of R. Ze'ira and his colleagues; it has no connection to his teaching above. Perhaps HA'GAON RAV C. KANIEVSKY, SHLITA explains so.

R. Yonah said, from Rav Huna's teaching, we learn that if one immersed three hyssop branches [in Mei Chatas], each by itself, and they were mixed, he may sprinkle from them.

(Rav Chisda): This is only if they came from three bundles.

According to R. Zeira and his colleagues, this is only if he immersed the three at once.

Suggestion: Perhaps we do not learn hyssop from Brachah!

Rejection: We see that Rabanan engage in the laws of Sukah, and learn from mud that pours (regarding a Mikveh)!

(Mishnah): If one distanced the Sechach from the walls three Tefachim, it is Pasul.

Inference: [If one distanced it] less than this, it is Kosher.

Question: May one sleep under [the gap between the wall and the Sechach]?

Answer (R. Yitzchak ben Elyashiv): Mud that pours can complete [the Shi'ur for] a Mikveh, but on immerse in it. Also here, [the gap] completes [the Shi'ur for] a Sukah, but one may not sleep under it.