Question: Why does it say "Chatas for Shegagah"? This (Par Helam Davar) itself is a Chatas!

It is not appropriate to say "they are Chayav Chatas only for something for which Chatas is brought for Shigegaso!"

Answer #1: Perhaps Agav (due to) other places where it says so regarding lashes, it says so also here.

Answer #2: It means that what someone else would be obligated a Chatas for Shegagah, here they bring a bull.

Implied question: Similarly, we could have learned an individual from "Mitzvos-Mitzvos", for it says "v'Im Nefesh Achas Techeta... b'Asosah Achas mi'Kol Mitzvos Hash-m"!

Answer: The Tana prefers to learn this way (the latter Parshah from the previous one).

Question: How can we learn from a Nasi? Nasi was learned from a Gezeirah Shavah. It cannot return to teach through a Hekesh, like it says in Zevachim (50b)!

Answer: This is a mere Giluy Milsa, and not a Hekesh, for both of them are individuals, and both are a Nefesh.

Question: Above (7b) it is difficult, for we learn from idolatry from other Mitzvos, and other Mitzvos from Zaken Mamrei. Something learned from a Gezeirah Shavah cannot teach through another Gezeirah Shavah!

Comment: See Zevachim. The Gemara resolved that something learned from a Gezeirah Shavah can teach through another Gezeirah Shavah! This requires great investigation. (Be'eros ha'Mayim - there, Rami bar Chama derived this from a Beraisa. Tosfos asks why he could not infer so from our Mishnah. Mishmeros Kehunah - it teaches through a Gezeirah Shavah only when there is nothing else to learn from the latter Gezeirah Shavah. Here, the Gezeirah Shavah teaches other matters.)

Answer: (The restrictions of learning Lamed (something learned from elsewhere) from Lamed apply only to Kodshim.) We follow the Melamed (source), and [here] the Melamed (Zaken Mamrei) is Chulin.

Explanation: Since he admits to [idolatry], what need does he have to fulfill all the Mitzvos? Presumably, he will transgress all of them.

Alternate source: The Sifri learns from "Es Brisi Hefer" - this connotes that he annuls the entire covenant.

Implied question: Why don't we bring those [Mitzvos] explicitly written [before Sinai], e.g. Milah was given to Avraham, murder, for it says "Shofech Dam ha'Adam...", and Arayos?

Answer: Here (at Marah), Yisrael were commanded. Those [Mitzvos were commanded to] Bnei Noach.

Explanation: In Shevuos (18a) it explains that he withdrew [his Ever from] a Nidah (e.g. she became Nidah in the middle of Bi'ah) amidst erection. His withdrawal is pleasurable like entering the Ever;

Rather, he should insert his fingernails in the ground [and support himself on his hands] and withdraw after the erection ceases.

Citation (Toras Kohanim): One is not liable for an Aseh, for it says "Asher Lo Sa'asenah";

Citation (cont.) Question: Perhaps I exclude even the Aseh in Nidah! "Mitzvas Hash-m" includes this. (The verse does not specify what to include.) Why do you include [the Aseh in Nidah, and not others Mitzvos Aseh]?

Citation (cont.) Answer: I exclude other Mitzvos, which do not have a Lo Sa'aseh, and I include the Aseh in Nidah, which has a Lo Sa'aseh.