WHEN DOES A TAMEI NAZIR SHAVE?
Support (for rejection): Presumably, this is correct. If it meant that he will shave like a Tamei Nazir (to remove the hair and allow Nezirus Taharah to begin), a Muchlat also shaves!
Rejection: No. It means that the former's hair will be shaved for Nezirus, but a Muchlat's hair will (be shaved due to Tzara'as, it will) not be shaved for Nezirus.
Answer #4 (Beraisa): "And the Nazir's head became Tamei" discusses a Tahor Nazir who became Tamei. He must shave and bring (Korbanos of) birds. It exempts one who was Tamei from the start from shaving and birds.
Suggestion: A Kal v'Chomer should obligate him. One who was Tahor and became Tamei must shave and bring birds, all the more so, one who was Tamei from the start!
Rejection: "And the Nazir's head became Tamei" discusses a Tahor who became Tamei. He shaves and brings birds, but one who was Tamei from the start does not.
WHEN DOES NEZIRUS TAHARAH BEGIN?
Question: Who is the Tana of the following Beraisa?
(Beraisa): The only difference between a Tamei who accepted Nezirus and a Tahor Nazir who became Tamei, is that the former counts the seventh day of becoming Tahor towards the term of Nezirus, but the latter does not.
Answer (Rav Chisda): It is Rebbi, who says that Nezirus Taharah does not start until day eight. It is unlike R. Yosi b'Rebbi Yehudah, who holds that it starts on day seven:
(Beraisa - Rebbi): "He will sanctify his head on that day" refers to the day he brings his Korbanos;
R. Yosi b'Rebbi Yehudah says, it refers to the day he shaves.
Question: Who is the Tana of the following Mishnah?
(Mishnah): If a Nazir became Tamei several times, he brings only one Korban (i.e. one set of Korbanos Tum'ah).
Answer (Rav Chisda): It is R. Yosi (b'Rebbi Yehudah), who says that Nezirus Taharah begins on day seven.
The case of one Korban for several Tum'os is when he became Tamei on day seven, and again on day seven.
Since he became Tamei before he could bring his Korban, he brings only one.
According to Rebbi, if he became Tamei on day seven, and again on day seven, this is like one long Tum'ah;
If he became Tamei on day eight, and again on day eight, since this was after he was able to bring his Korban, he would need to bring a Korban for each Tum'ah!
Question: What is Rebbi's reason?
Answer: Immediately after "he will atone for him for his sin of the Nefesh", it says "he will sanctify his head"! (This shows that they are on the same day.)
R. Yosi: If so, the verse should end "he will sanctify his head"!
Question: Why does it add "on that day"?
Answer: Without this, we would say that he starts Nezirus Taharah on day eight. This teaches that he starts on day seven.
Question: How does Rebbi expound "on that day"?
Answer: It teaches that he starts on day eight even before bringing his Korban.
Question: What forced Rav Chisda to explain that the Mishnah is like R. Yosi? He could explain like Rebbi, in a case when the Nazir became Tamei on the night of the eighth!
Suggestion: He did not say so, because he holds that the previous night is not Mechusar Zman (rather, it is as if the time for the Korban has arrived, and he would have to bring a Korban for each Tum'ah).
Answer (and Rejection of suggestion - Rav Ada bar Ahavah): The beginning of Nezirus Taharah and the obligation for another Korban depend on each other. (Therefore, in any case the Mishnah cannot be like Rebbi.)
If the previous night is Mechusar Zman , Nezirus Taharah does not start until morning, (and it is like one long Tum'ah).
If the previous night is not Mechusar Zman, Nezirus Taharah starts on the night before the eighth (and he must bring a Korban for each Tum'ah)!
(Beraisa - Rebbi (Eliezer - the Gra deletes this): If he became Tamei on day seven, and again on day seven - he only brings one Korban;
If he became Tamei on day eight, and again on day eight, he brings a Korban for each Tum'ah;
He begins Nezirus Taharah immediately;
Chachamim say, he brings one Korban for all the Tum'os, unless he already brought the Chatas;
If he brought the Chatas and became Tamei, brought the Chatas (for the latest Tum'ah) and became Tamei, he brings (the remaining) Korbanos for each Tum'ah.
If he brought the Chatas, and did not bring the Asham, he begins Nezirus Taharah;
R. Yishmael, the son of R. Yochanan ben Berokah, says, just like he does not begin (Nezirus Taharah) until bringing the Chatas, he does not begin until bringing the Asham.
Question: We understand Rebbi (Eliezer). It says "He will sanctify his head on that day", even before bringing his Korbanos;
Chachamim expound, "on that day" - even though he has not brought his Asham.
How does R. Yishmael expound "on that day"?
Answer: He begins, even though he has not brought his Olah.
Chachamim do not need a verse to teach this. The Olah is a mere gift to Hash-m. It is not needed for atonement.
Question: What is Chachamim's reason?
Answer (Beraisa) Question: What do we learn from "V'Hezir (he will conduct Nezirus Taharah)... and he will bring... an Asham"?
Answer: We find that all (other) Ashamos in the Torah are essential to atonement. One would have thought that also Asham Nazir is Me'akev! "V'Hezir... and he will bring" teaches that even before he brings, he is a Nazir.
R. Yishmael expounds "V'Hezir... and he will bring" - he is a Nazir after he brings.