Observation: This was already taught above (5a). Since the Tana needed to teach that if he shaved or bandits shaved him, he cancels 30 days, he taught also that Stam Nezirus is 30 days.

Explanation: The reason he cancels 30 days is because he needs like the term of Stam Nezirus when he shaves for a Mitzvah, that his hair is big like is proper to grow in a Stam Nezirus, i.e. 30 days;

We discuss when they shaved him on Yom Melos. If they shaved him or bandits shaved him two or more [days from the end of Nezirus], why does he cancel everything? Rather, he [counts the days that remained, and] returns to count again the number of days he counted!

Note: Tosfos asks why the Mishnah says that he cancels "everything", i.e. 30 days. Perhaps the text should say "Yistor Lamed".

Suggestion: Perhaps indeed, the Mishnah means this! He cancels until his hairs will be like [growth of] 30 days. It says so in the Perush of R. Yitzchak.

Consequence: Therefore in a Nezirus of 60 days, if they shaved him on day 30, he does not cancel anything, for there is still time to grow hair before the day of shaving;

If they shaved him after his days finished, and there is no growth of hair, he cancels 30 days according to Rabanan, like is proven in the Gemara.

Explanation: [In] all seven days, the hairs grow only enough to bend [them to the roots]. Therefore, [if this amount was left] he does not cancel anything, for the growth in the seven days of Stirah [for one whose hair was totally shaven] is only enough to bend.

Consequence: We require at the time of shaving only that the hairs of his head are big enough to bend;

Also if they shaved him after Melos, and left enough to bend, he does not cancel [anything]. However, surely shaving within Melos cancels 30 days, like below, due to [the need for] growth of hair.

However, when they shaved him after Melos, since there was in front of us growth of hair on day 30 proper for shaving, like we said, mid'Oraisa this suffices;

However, he must wait seven days. We learn from Tiglachas Tum'ah.

Implied question: These are not totally similar! There, he must wait seven days in order to bring his Korbanos in Taharah!

Answer: In any case, Chachamim equated Stirah of shaving after Melos to Stirah of Tum'ah.

Distinction: However, according to Rabanan, surely since if he became Tamei after Melos he cancels 30 days, like we say above (16a), similarly we learn every Tiglachas from Tum'ah after Melos to be Soser 30 days, just like Tum'ah;

We require at the time of shaving 30 days growth of hair. Also when they shaved him after Melos, he cancels 30 days;

What they left on him, in order to bend the end [of the hairs] to the roots, does not suffice, unless they left on him what is proper to grow in 30 days. Therefore, we establish it specifically like R. Eliezer.

Possibility #1: Surely, we could establish it also according to Rabanan, e.g. if they shaved him on day 32 or 33;

Rabanan agree that if he became Tamei on day 32 that he cancels only seven days, like I explained above.

Possibility #2: (We had to establish it like R. Eliezer.) Perhaps Rabanan agree here after Melos, that he will bring his Korban, and he does not cancel anything. (I.e. they agree that he does not cancel 30 days. However, they do not require any remnant to his hair, unlike R. Eliezer, who holds that he cancels seven days if they are too small to bend);

Only according to R. Eliezer, who says that Tiglachas is Me'akev, that if they shaved him and did not leave enough to bend, he cancels seven days, so he can shave again and bring his Korbanos.

However, according to Rabanan, who says that Tiglachas is not Me'akev, he does not cancel anything. He may drink wine immediately after he brought his Korbanos.

Implied question: Also Rabanan require Tiglachas Mitzvah, and he must wait seven days! (If so, we can establish it like Rabanan!)

Answer: The expression "he does not cancel" connotes that if did not leave [enough to bend], he must cancel, i.e. there is an Isur of Nezirus on him;

Either he may not drink wine or do some other matter as long as he did not shave again. According to Rabanan, there is no Isur on him.

Explanation: Only [for shaving with a razor] he is lashed.

Citation of Gemara: If he uprooted any amount.

Explanation: [We ask, if he uprooted] without a razor, whether he uprooted from its source, near his scalp, however, without a razor, or if he did not totally uproot it, rather, only partially, what is the source that it is forbidden?

[We answer] "Kadosh Yihyeh Gadel Pera" - the Mitzvah is to grow hair. He transgresses an Aseh if he shaves from it at all, even if he does not totally cut it from its source;

However, if he totally cuts it from its source, like a razor [does], there is a Lav for all way of [totally] removing hairs, like the other Beraisa teaches. [R. Yoshiyah and the other Beraisa] do not argue with each other;

However, this Tana (R. Yoshiyah) prefers to cite "Kadosh Yihyeh Gadel Pera", for we learn from it an Isur [Aseh] even if he does not totally cut it from its source. (The other Tana learns a Lav from "Lo Ya'avor" for anything that totally cuts it from its source.)

Explanation: [We ask for the source that he is lashed for any amount, i.e.] even one hair;

[We answer that] "Lo Ya'avor Al Rosho" includes everything that removes, as long as it is like a razor, which totally uproots from its source.

Observation: Also the Tana of our Mishnah holds like this Tana, and like the first Tana who argues with R. Yonason (i.e. R. Yoshiyah).

Explanation: [We ask, since in the end we include everything, i.e.] even other matters that remove [why did the Torah need to write Ta'ar]?

Citation of Gemara: Why did the Torah write Ta'ar?

Explanation: [We ask,] for if [it wrote Ta'ar] to teach what cuts like a razor, it should have written "Mashchis"!

Explanation: A Metzora is more stringent [than a Nazir], because he must shave all the hair on his body, for it says "v'Hayah va'Yom ha'Shevi'i Yegalach Es Kol Se'aro Es Rosho v'Es Zekano..."

You cannot learn [from a Metzora] to a Nazir, which is lenient. He needs to shave only his head, like the verse explicitly says. Therefore, [one might have thought that] he does not require a razor. Therefore, it says "Ta'ar Lo Ya'avor";

Since we do not need it for the Isur of removing hair during his Nezirus, for one is lashed even for all matters that [totally] remove, we apply it to shaving for a Mitzvah, at the end of Nezirus, that it is only with a razor.