R' Yochanan: (In the same Mishnah in Shabbos, there were two babies, one was scheduled to have his circumcision on Shabbos and the other was to have it on Friday; he forgot and on Shabbos he circumcised the baby who was scheduled to have it done on Friday, he is exempt.) This is the opinion of R' Meir who said that if its performance is a Mitzvah, he is exempt and if it is not a Mitzvah, it is a dispute (between R' Eliezer and R' Yehoshua - see 71-2 (c)).

R' Shimon: One who did an act whose performance is not a Mitzvah is liable; if it is a Mitzvah, it is a dispute. (Note: The last two entries follow the text of the Korban HaEidah.)

R' Yosi quoting R' Yehoshua: The statement of R' Meir applies when it is an unblemished lamb, a year old and it is a Shelamim, so it is suitable to change into a Pesach.

One can learn three requirements from this statement -

It must be exchanged for a sacrifice that has no limit.

It must be normal to change its identity (unlike a calf that is not normal to exchange with a Pesach or a Tamid).

Its performance must be a Mitzvah (as a Shelamim is valid, even if slaughtered as a Pesach).

Question: What is an example of something that does not have a limit?

Answer #1: R' Yirmiyah thought to say that all sacrifices that override Shabbos do not have a limit, as the Torah did not write how many sacrifices override Shabbos - whenever Yom Tov or Rosh Chodesh occur on Shabbos, they override it.

Answer #2: R' Yosi thought to say that an example of no limit is a sacrifice that cannot be counted (such as a Pesach, where the exact number cannot be calculated in advance).

When R' Yosa reached the Mishnah (in Shabbos) of two babies (where R' Eliezer and R' Yehoshua disagreed), he said - R' Yirmiyah taught us well; could one say here that the acts have no limit (the details of the two babies are known)? Rather, R' Yirmiyah is correct and the Torah did not give a limit how many Pesach offerings will override Shabbos each year.

R' Chisda: One can explain the words of R' Shimon (who said that there is a dispute about an act that was a Mitzvah) as referring to when there was one group who did not slaughter - their minds are busy with performing the Mitzvah.

R' Zeira: The statement of R' Yannai was when he forgot and on Friday he circumcised the baby who was scheduled to have it done on Shabbos.

Question: If he circumcised both babies on Shabbos - the Shabbos baby's circumcision was done in the morning and the other baby's (whether it was scheduled for Sunday or Friday) circumcision was done in the afternoon -

R' Yannai said that he is exempt.

R' Aba said that he is liable.

Question (against R' Aba): If this is true, why did the R' Yannai teach a case of when he circumcised the Shabbos baby on Friday - even if he performed it on Shabbos he is liable!

Answer: To teach a case where the babies were mixed up and he becomes liable.

According to R' Zeira, R'Yannai follows R' Meir (that whenever a person's mind is busy with a Mitzvah, he is exempt).

R' Mana to R' Yosa: R' Chisda's statement (see earlier (i) - that there was one group who did not slaughter), follows R' Shimon (who said that if he forgot and circumcised the Sunday baby on Shabbos, that all agree he is liable). R, Yannai (he forgot and circumcised the Shabbos baby on Friday), follows R' Meir (as explained).

Question: If so, what is the difference between R' Meir and R' Shimon (both require him to have his mind busy with a Mitzvah)?

Answer: They disagree over many things (such as something that has a limit and something that its identity is not usually changed).

Question: One who has two babies to circumcise - are they viewed as something that does or does not have a limit?

Answer: If you view it as something that does not have a limit, even if he circumcised the Shabbos baby on Friday, he is exempt; and if you view it as something that does have a limit, there must be another baby that needs circumcision in order that he be considered busy with the Mitzvah - without that, he is liable.

Question: According to R' Yehoshua (of the Mishnah in Shabbos), if he circumcised the Sunday baby on Shabbos, even though he has not done a Mitzvah, he is exempt. But if he circumcised the Friday baby on Sunday, when he has done a Mitzvah, why do all agree that he is liable?

Answer (Rav Huna): The text of the Mishnah must be switched, as R' Shimon taught - R' Eliezer and R' Yehoshua agree over a person who should have circumcised on Sunday and performed it on Shabbos, that he is liable. They only disagree over a person who should have circumcised on Friday and performed it on Shabbos - R' Eliezer said that he is liable and R' Yehoshua said that he is exempt.

R' Yosi bei R' Bun: This strong question (that caused the text to be switched) was also a question for R' Yannai and answered that the first case was that the person had already circumcised the Shabbos baby on Friday. Therefore, there was no baby to circumcise on Shabbos and all agree that he is liable.

Rav Ada bar Achva: These are the words of R' Meir and R' Shimon; however, R' Yosi says that even if it was an act that was not a Mitzvah, since he mistaken thought that it was a Mitzvah, he is exempt.

If he removed his hand upon completion of the circumcision, he may only return to remove strips of skin that are crucial to the successful performance of the circumcision.

R' Yochanan: According to R' Yosi, he may even return to remove strips of skin that are not crucial.

Question: To which statement of R' Yosi is he referring?

Answer (Mishnah): R' Yosi says - If the first day of Succos occurred on Shabbos and he forgot and took his Lulav out into the public domain, he is exempt as he took it out with 'permission'.

Query: Does this also apply to a circumcision knife (after the circumcision)?

Query #2: Does this also apply to Matzah (if there is a larger quantity than is required for the Mitzvah)?

Answer: The statement of R' Yochanan about R' Yosi, that he may even return to remove strips of skin that are not crucial, proves that this would also apply to circumcision and Matzah.