To whom is "Tedaber" referring?
Ramban #1 and Moshav Zekenim #1: Moshe was instructing Aharon, the one who was in charge of Korbanos, to instruct the people what they must bring, in order to boost his esteem in the eyes of the people.
Ramban #2 and Moshav Zekenim #2 : Moshe instructed Aharon and the elders (mentioned in Pasuk 1) to instruct the people what they must bring.
Ramban #3: Moshe instructed Aharon to take the prescribed Korbanos for himself and the elders - mentioned in Pasuk 1 - to instruct the people what they must bring.
Why did Moshe instruct Aharon to tell Yisrael what to bring? Why did he not personally instruct the Zeknei Yisrael who were there at that meeting?
Ramban: Refer to 9:1:1:1.
Oznayim la'Torah: So that, when he (Aharon) instructed them whyat o bring, he would atone for his instructions "Parku Nizmei ha'Zahav ... ve'Havi'u Eilai" and "hag la'Hashem Machar" that he issued by the Eigel ha'Zahav. 1
See Oznayim la'Torah DH 've'el B'nei Yisrael" #1.
Why were the people told to take specifically a goat as a Chatas and a calf and a lamb as an Olah?
Ramban: The goat atoned for dipping Yosef's shirt in the blood of a goat, and the calf 1 for the sin of the Golden Calf. 2
Targum Yonasan: The goat, to prevent the Satan - who is compared to a goat - from prosecuting them for the kid-goat that they Shechted when Yakov's sons sold Yosef in order to trick their father; the calf, because they worshipped the Golden Calf, and the lamb, so that Hashem should recall on their behalf the merit of Yitzchak, who was bound like a lamb.
Moshav Zekenim: Great is the power of a Tzibur! Hashem did not want to shame them to bring a calf as a Chatas like Aharon (since it clearly atones for the Eigel 3 ), but a goat, like a regular Chatas for idolatry. 4 They were Az (brazen) to say "Eileh Elokecha Yisrael", therefore they bring a Se'ir Izim. However, He commanded to bring as Olos a calf with a lamb. He desired their Teshuvah so much that He chose a lamb, which is brought for the Tamid, to bring with the calf. 5 Or, the lamb corresponds to Ya'akov and the Shevatim, since Aharon did not bring he same as them.
Da'as Zekenim: Since they were told to take a calf, they knew that they were pardoned for the Golden Calf.
Oznayim la'Torah: The lamb as an Olah came to apease Hashem following the Chatas that came to atone ? as is normally the case.
All the Korbanos listed here are equivalent to the Korbanos of the Kohen Gadol and the people on Yom Kipur - which came to atone for the same sins (Ramban).
Moshav Zekenim: Since the Torah writes "Se'ir Izim le'Chatas ve'Eigel" to hint that it is for the Chet ha'Egel.
The Chatas for Avodah-Zarah is specifically a goat (and not a lamb).
How does this show that He desires their Teshuvah? Perhaps the Tamid shows that the closeness of Yisrael to Hashem; bringing these together shows that Hashem wants to return to the same closeness. (PF)
Why did Aharon bring a Chatas to atone for his participation in the Eigel, and Yisrael, an Olah?
Oznayim la'Torah: Because Aharon sinned be'Shogeg, for which the atonement is a Chatas, whereas, bearing in mind that all those who actually worshipped the Eigel where either killed by the B'nei Levi or died in the subsequent plague, 1 sinned either in thought alone or by not rebuking those who sinned, both of which are only subject to an Olah. 2
Rashi (in Pasuk 7) writes that we learn from here that an Eigel is a yearling. We say about testimony that "Eid" is always two, unless the Torah specifies one. Also here, we should say that Eigel is in its second year, unless it says "ben Shanah"!
Riva: We cannot say sohat, since "E'gel" does not imply ben Shetayim more than ben Shanah, whereas "Eid" implies two, since [normally] testimony is not less than two. 1
We know this from elsewhere - "al-Pi Sh'nei Eidim? Yakum Davar" (Shoftim Devarim 19:15. - PF)
QUESTIONS ON RASHI
Rashi writes - in Pasuk 7 -that we learn from here that an Eigel is a yearling. If so, why did the Torah write fifty-one times regarding lambs 'ben Shanah'? Why do we not likewise say that having written once "ben Shanah", we know for all time that "Keves" ie 'ben Shanah'?
Perhaps these are fifty-one Kesuvim ha'Ba'im ke'Echad. The only 'Kevasim' written about Korbanos where it does not specify a yearling are Chatas 1 , the male lambs of a Metzora 2 , and Nesachim 3 (4:32, 14:10, 21, Bamidbar 15:5). (PF) Meshech Chachmah (5:6) - Parah 1:3 teaches that "Keves" is always a yearling 4 . "Kesev" includes older animals - Olah and Shelamim, the Isur of Chelev, Shechutei Chutz, Ba'al Mum and the Heter to eat them (1:10, 3:7, 7:23, 17:3, 22:19, Devarim 14:4). Sometimes Chata'os are called "Kesev" (4:35, 5:6) even though they are yearlings.
The Torah specified that a goat Chatas for idolatry must be a yearling (Bamidbar 15:27). "Torah Achas Yih'yeh lachem" (ibid., 29) teaches that the same applies to all Chata'os (Sifra, Chovah 7:10:2. Malbim (283) - we need not learn to Kesavim, since the Torah always says "b'nei Shanah", and after a year it is called a ram. Rashi (Kidushin 55b) - every "Kisbah" is a yearling. (Refer to 9:3:153:1***.)
Perhaps we learn from a Metzora's Kivsah; the same Pasuk calls it a yearling. However, if so, we could learn also "Temimim" from the Kivsah; why did the Torah write "Temimus" by both of them? (PF)
The Torah specified Nesachim for Kevasim and rams. In Menachos, 91b, Bar Pada was uncertain what is the Nesech for a Palgas (a sheep in its 13th month; perhaps it is included in Keves). R. Yochanan holds that it is a new entity, and "O la'Ayil" teaches about it. (Surely, he holds that after twelve months it is not called "Keves"! - PF)
Also Tiferes Yisrael there says so. The Rishonim did not say so; they could explain the Mishnah to teach that whenever Keves must be a yearling, this is from day to day. (PF)
