Seeing as the firstborn were already sanctified in Egypt (See Sh'mos 13:2), why were they redeemed only now?
Ramban #1: Because until now, bearing in mind that the Kohanim had not yet been appointed, there was nobody to whom to give the redemption money.
Ramban #2 (based on Zevachim 112b): In Egypt, they were sanctified to offer Korbanos, 1 Now however, due to the sin of the Eigel, Hashem chose Levi to replace them, and they had to be redeemed.
Seforo: Refer to 3:13:1:1***.
See Rashi Sh'mos 24:5.
Which firstborn is the Pasuk referring to? When were they born?
Which firstborn animals did the animals of the Levi'im exempt from the Bechorah?
Why did the firstborn Tahor animals of the Levi'im not redeem the firstborn Tahor animals of the Yisre'elim?
Oznayim la'Torah: Because, as opposed to the Pitrei Chamor,which were only Kadosh Kedushas Damim, the Bechorim of Tahor animals are Kadosh Kedushas ha'Guf, which cannot be redeemed, and were brought on the Mizbe'ach and eaten by Aharon and his sons in the course of time. 1
Or, due to the sheer force of numbers, were burnt according to the opinion - in Bechoros, 4b - that they brought all of them on the day that the Mishkan was erected. See Oznayim la'Torah, who also cites an opinion in Bechoros that the firstborn Tahor animals of the Levi'in also redeemed the firstborn Tahor animals of the Yisre'elim.
Having already written "Vehayu Li ha'Levi'im" in Pasuk 12, why does the Torah repeat it here?
Bechoros, 4b: With reference to the firstborn of the Kohanim and the Levi'im redeeming themselves, 1 the Torah is teaching us that they will continue to do so for all generations. 2
See Torah Temimah, note 17.
Even though the Kal va'Chomer (cited in 3:47:151:1) is no longer applicable.
QUESTIONS ON RASHI
Rashi writes that the Levi'im's animals exempted only Pitrei Chamorim of Yisrael. In Bechoros 4a, Abaye learned from a Kal va'Chomer from the Midbar that the lambs of the Levi'im are exempt. Rava said that if so, even their Tahor animals (including cattle) should be exempt (and that is also how Rashi explained it there)?
Moshav Zekeni (citing R. Avigdor): The Kal va'Chomer is that if even a Pashut (a non-firstborn) lamb of a Levi exempts a Peter Chamor, all the more so should it exempt its own firstborn from Kedushas B'chor. Rava argued that if so, even a firsborn lamb of a Levi should be exempt. Do not say that they exempted Yisrael's animals, for there is no Pidyon for a B'chor of a Tahor Beheimah, since Pidyon is confined to human Bechoros and donkeys.
