(Mishnah): If one had two babies to circumcise, one on Shabbos and one the next day, and he mistakenly circumcised the latter on Shabbos, he is Chayav [Chatas];

R. Eliezer says, if one baby should have been circumcised on Erev Shabbos and the other on Shabbos, and he mistakenly circumcised the former on Shabbos, he is Chayav Chatas;

R. Yehoshua exempts.

(Gemara - R. Yochanan): Our Mishnah is R. Meir, who says that if one did [a Melachah on Shabbos that] the action is a Mitzvah, he is exempt. If [he intended to do a Mitzvah] and his action was not a Mitzvah, there is an argument [of R. Eliezer and R. Yehoshua] about this;

R. Shimon says, an action that is not a Mitzvah, he is liable. If it is a Mitzvah, there is an argument about this.

(R. Yosi citing R. Yochanan): (In Pesachim 6:5, if one slaughtered a Korban l'Shem Pesach on Shabbos, R. Eliezer obligates, and R. Yehoshua exempts.) R. Shimon says, this is only if it is Tam yearling Seh, and [it must be] a Shelamim, which is proper to change to l'Shem Pesach.

We learn three things from this. We learn that it must be [l'Shem] something without limit (how many may be offered that day, but not Tamid or Musaf), it must be something that is prone to be switched (but not a calf), and it must be something that there is a Mitzvah to do it (e.g. offering a Shelamim).

Question: What matter has no limit?

Answer #1 (R. Yirmeyah): The Torah did not limit how many Pesachim are Docheh Shabbos every year.

Answer #2 (R. Yosi): You cannot know that the number [of Pesachim. Therefore, it is reasonable that he thought that also this is a Pesach.]

Retraction: When R. Yosah reached [our Mishnah] of Safek babies, he said "R. Yirmeyah taught me properly! Can you say that one cannot count them?! Rather, the Torah did not limit how many Pesachim are Docheh Shabbos every year.

Defense (of R. Yosi - Rav Chisda): R. Shimon discusses when there was not one group that did not yet slaughter [therefore, R. Yehoshua exempts only something without a limit. If there is a group that did not yet slaughter, since there is a Mitzvah that overrides Shabbos, he is exempt even if there is a limit. Therefore, there is no question from the case of babies to Shechitah l'Shem Pesach.]

(R. Ze'ira): R. Yanai's words shows that [in the Reisha of our Mishnah, all obligate] when he forgot and circumcised the baby [that he should have circumcised on] Shabbos on Erev Shabbos [so there was no Mitzvah of Milah to do on Shabbos].

If he circumcised in the morning [the Shabbos baby, and in the afternoon the baby for Sunday], R. Ze'ira said that R. Yanai exempts [for there was a Heter to circumcise on Shabbos]. R. Ba said that he is liable [for at the time he did the latter baby, there was no Heter to circumcise any baby here].

Question (against R. Ba): Why did R. Yanai say [that in the Reisha, he circumcised the Shabbos baby on Erev Shabbos? You say that even when he circumcised him on Shabbos morning, he is liable for the latter!]

Answer: He [merely] came to teach how the babies were mixed up. (He circumcised the Shabbos baby on Erev Shabbos, for he thought that it is the Erev Shabbos baby, and the remaining baby is the Shabbos baby. R. Yanai did not mean that R. Yehoshua obligates only in this case. )

R. Ba (who obligates if he circumcised at a time when there was no baby that overrides Shabbos) holds like R. Yanai (who says that all obligate when the Shabbos baby was circumcised before Shabbos). R. Zeira (who exempts even if he circumcised when there was no baby that overrides Shabbos) holds like R. Meir [who exempts one who slaughtered l'Shem a Korban Tzibur, even if the Korban Tzibur was already slaughtered, even though there is a limit. We explained this like NO'AM YERUSHALMI, Pesachim 6:5.]

Question (R. Mana, to R. Yosi): (Above, why did R. Ze'ira need to counter Rav Chisda's opinion and teach differently?) Rav Chisda [who said that there was not one group that did not yet slaughter] discusses according to R. Shimon. R. Yanai [who said that all obligate when he circumcised the Shabbos baby on Erev Shabbos] discusses according to R. Meir. Do we challenge [and need to resolve] a difficulty between R. Meir and R. Shimon? We find that R. Meir and R. Shimon argue!

Question: (We find an argument between R. Meir and R. Shimon about confusion of babies.) In other cases of Safek babies (e.g. it is not known which day he is born), do you compare this to something with a limit (R. Yehoshua agrees that one who slaughtered l'Shem Korban Tzibur is liable, for it has a limit), or something without a limit [like Pesach, for which he exempts]?

If you consider [babies] like something without a limit, [R. Yehoshua exempts only if] there is no baby to circumcise [today].

If you consider [babies] like something with a limit, [he exempts only if] there is one baby to circumcise [today].

Answer (R. Yosah): Rabanan's words [in our Mishnah, and in Pesachim] show that they consider them like something with a limit. [R. Yehoshua exempts only if] there is one baby to circumcise. (We explained this like PNEI MOSHE.)

Question: If he [circumcised] too early (the baby for Sunday on Shabbos, and did not do a Mitzvah), he is exempt. If he [circumcised] too late (the baby for Friday on Shabbos, and did a Mitzvah), he is liable?!

Answer #1 (Rav Huna): [R. Shimon] switches our Mishnah;

(Beraisa - R. Shimon): R. Eliezer and Yehoshua did not argue about one who should circumcise after Shabbos, and he circumcised on Shabbos, that he is liable. About what did they argue? About one who should circumcise on Erev Shabbos, and he circumcised on Shabbos. R. Eliezer obligates, and R. Yehoshua exempts.

Answer #2 (R. Yosi bei R. Bun): Due to this question, R. Yanai said that they argue about when he forgot and circumcised the Shabbos baby on Erev Shabbos.

(Rav Ada bar Ahavah): This is according to R. Meir and R. Shimon, but R. Yosi says that even something that it is not a Mitzvah to do it, since he erred and did it l'Shem Mitzvah, he is exempt.

If one separated [from circumcising on Shabbos], he may return to cut only strands that are Me'akev Milah.

(R. Yochanan): R. Yosah holds that even if he separated, he may return to cut even strands that are not Me'akev Milah.

Question: Which teaching of R. Yosi [shows this]?

Answer (Mishnah - R. Yosi): If the first Yom Tov of Sukos occurred on Shabbos, if one forgot and was Motzi a Lulav to Reshus ha'Rabim, he is exempt, for he was Motzi with permission. (Even though he was Yotzei once he picked it up, there is somewhat of a Mitzvah to continue holding it. Likewise, it is Hidur Mitzvah to cut even strands that are not Me'akev Milah.)\what source l'Chatchilah?

Question: Does the same apply to a Milah knife or Matzah (if he took it out after the Mitzvah, is he exempt)?

Answer: Since R. Yochanan said that R. Yosi holds that even if he separated, he may return to cut even strands that are not Me'akev Milah, this teaches that even a Milah knife or Matzah is so (if he took it out after the Mitzvah, he is exempt).