WHY IS ONE LIABLE FOR A PASUL SLAUGHTER?
(Mishnah): If he slaughtered Pesach Lo l'Ochlav...
Objection: Obviously, since the Korban is Pasul he is liable [for Chilul Shabbos]!
Answer #1: This is for parallel structure with the Seifa, which exempts [for l'Ochlav and Lo l'Ochlav].
Objection: Also that is obvious - since the Korban is Kosher he is exempt!
Answer #2: Rather, it is for parallel structure with the Reisha, which obligates for Lo Lishmah.
Question: Also the Reisha is obvious [since it is Pasul]!
Answer: The Reisha was taught to introduce the argument of R. Eliezer and R. Yehoshua [about other Korbanos l'Shem Pesach - but all agree about Pesach Lo Lishmah].
Question (Rav Huna bar Chinena): According to the opinion that one who wounds unproductively is exempt, why is one liable for slaughtering Lo l'Ochlav - it is not productive!
Answer: [Regarding Pesulim that apply only in the Mikdash] 'Im Alu Lo Yerdu' (if the Chelev was brought on the Mizbe'ach it is offered, it is not brought down).
Question (Mishnah): If he slaughtered and found that it has a Mum, he is liable.
What did the slaughter accomplish?!
Answer: The Mum was a film over the eye - this is like R. Akiva, who says 'Im Alu Lo Yerdu' about such [minor] Mumim.
Question (Mishnah): If he slaughtered it and then found that it has an internal Tereifah, he is exempt.
Inference: If it was openly Tereifah, he is liable.
What did the slaughter accomplish? (R. Akiva admits that we never offer a Tereifah!)
Answer: The slaughter prevents the animal from becoming [Tamei like a] Neveilah.
Question (Ravina - Beraisa): If on Shabbos one slaughtered a Chatas outside the Mikdash for idolatry, he brings three Chata'os.
What did the slaughter accomplish? (The carcass is forbidden and Tamei because it was offered to idolatry!)
Answer (Rav Avira): Slaughter makes it cease to be Ever Min ha'Chai (it is now permitted to Nochrim).
IS AKIRAH NEEDED?
(Mishnah): If he slaughtered it and then found [that the owners withdrew...]
(Rav Huna citing Rav): If an Asham (which cannot be offered, e.g. the owner offered a different animal for his Asham) was Nitak (given to a shepherd) to graze [until it becomes blemished, and to buy Nedavah (Olos of the Tzibur) with its Damim (redemption money)] and slaughtered Stam (without special intention), it is a Kosher Olah.
Inference: He holds that Akirah is not needed.
Question: If so, also Nituk should not be required!
Answer: Indeed, letter of the law it is not needed [after the owner got Kaparah by offering a different animal for his Asham] - Chachamim decree to require Nituk after Kaparah on account of before Kaparah (then it is still an Asham).
Question: What is the source of this?
Answer (Mishnah): If the owner of an Asham died, or if he brought a different animal in place of it [because it was lost], the Asham grazes and the Damim is used for Nedavah;
R. Eliezer says, it must die;
R. Yehoshua says, Olah is brought with the Damim.
Inference: Olah is brought with the Damim, but it itself is not offered for an Olah - we decree after Kaparah on account of before Kaparah.
Question (Rav Chisda - Mishnah): If he slaughtered it and then found that the owners withdrew...
(Beraisa): If this happened on a weekday, it would be burned immediately.
We understand this if Akirah is required - it is a Pesach without owners, which is Pesul ha'Guf (intrinsically Pasul), therefore it is burned immediately;
But if Akirah is not required, it is automatically a Shelamim - it is not Pesul ha'Guf, rather, because it was slaughtered after the afternoon Tamid - it should require Ibur Tzurah (to become Nosar before burning it)!
(Beraisa): Any Pesul ha'Guf is burned immediately; if it is Pasul on account of the blood or the owners, it is burned in Beis ha'Sereifah after Ibur Tzurah.
Answer #1: Rather, Rav Huna must have said that if it (an Asham Nitak to graze) was slaughtered l'Shem Olah, it is Kosher.
Inference: He holds that Akirah is needed.
Objection: R. Chiya bar Gamda said that Akirah is needed when the owners were Tamei Mes on Pesach and detained to Pesach Sheni (the Korban is destined to be offered l'Shem Pesach Sheni);
A normal Pesach [which cannot be offered l'Shem Pesach] does not need Akirah!
How can he answer?
Answer #2 (Rav Huna brei d'Rav Yehoshua): [Really, Rav Huna is Machshir even if it was slaughtered Stam;] the case is, the Pesach was Hukdash before midday and the owners died after midday;
It was Nir'eh v'Nidcheh (it was once Kosher to be offered, then it became Pasul) - this can never become Kosher again (therefore, Ibur Tzurah is not required).
Objection: We seek to explain Rav's teaching - Rav holds that a living being is never Nidcheh (when the Pesul goes away, it is Kosher again)!
Answer #3 (Rav Papa): The Beraisa is R. Eliezer, who says (Zevachim 2A) that another Korban slaughtered l'Shem Pesach is Pasul, it is Pesul ha'Guf (it is not on account of the owner or blood).
Objection: If it is R. Eliezer, he should be Chayav Chatas, for R. Eliezer does not exempt one who erred due to obsession with a Mitzvah!
Answer #4 (Rav Yosef brei d'Rav Sala Chasida): The Beraisa is Yosef ben Chunai:
(Mishnah - Yosef ben Chunai): Any other Korban slaughtered l'Shem Pesach or Chatas is Pasul.
It is Pesul ha'Guf - therefore, Ibur Tzurah is not required;
He exempts [one who erred due to obsession with a Mitzvah] like R. Yehoshua.
Answer #5 (Rav Ashi): Rav holds like R. Yishmael, son of R. Yochanan ben Brokah:
(Beraisa - R. Yishmael, son of R. Yochanan ben Brokah): If there was time during the day to find out that the owners withdrew, died, or became Temei'im, he is liable; it is burned in Beis ha'Sereifah after Ibur Tzurah.
Suggestion: It is not burned immediately because it does not need Akirah (it was a Shelamim; the only Pesul is that it was slaughtered after the afternoon Tamid)!
Rejection: Perhaps he holds like Tana d'vei Rabah bar Avuha, who says that even Pigul requires Ibur Tzurah - he learns from a Gezerah Shavah "Avon-Avon" from Nosar.
Support: We must say this to explain when the owners became Temei'im - surely Akirah is needed (the Korban can be brought for Pesach Sheni)!
(R. Chiya bar Gamda): The case is, the owners were Tamei Mes on Pesach and detained to Pesach Sheni - therefore it needs Akirah.
Conclusion: We must rely on Answer #4, the Beraisa is Yosef ben Chunai.