What was the purpose of Nachshon's sin-offering?

Question

Nachshon ben Amminadav, and each of the eleven tribal leaders who followed him, offered "one young he-goat for a sin offering" as part of their gifts for the dedication of the Mishkan (Num. 7:16 passim). Rashi there, citing Sifri, states that this was

to atone for [uncleanness caused by] a grave in the depths [i.e., an unknown grave which may lie in the earth over which people unknowingly pass, rendering them unclean],which is a [case of] uncertain contamination.

But in his commentary to Lev. 10:17, he points out (citing Sifra) that the sin offering that Aharon's sons burned (instead of eating it) must have been the one brought in honor of Rosh Chodesh, since Moshe identifies it as an offering brought "to gain forgiveness for the sin of the community," and Nachshon's offering was not brought for purpose of atonement.

[The sin offering of Rosh Chodesh is meant to atone for cases where "there was no knowledge [of being impure] at either the beginning [before entering the Beis Hamikdash or eating sacred food] or at the end [after having done so]" (Rambam, Hil. Shegagos 11:9, from Shevuos 2a).]

So in that case, isn't Nachshon's offering indeed for purposes of atonement - indeed, it is largely similar to what's covered by the Rosh Chodesh offering?

Answer 1

The Maskil LeDavid on Rashi in Vayikra 10:17 asks the same question. He says that we must say that all the sin offerings were coming to atone for something, that's the nature of a sin offering. Rashi (Vayikra 10:16) tells us that 3 sin offerings were brought that day, and the Maskil LeDavid explains what they were for:

• “[Take] a he-goat [as a sin-offering]” (Lev. 9:3) -- To atone for the sale of Yosef

• the he-goat of Nahshon [the son of Aminadab, leader of the tribe of Judah] (Num. 7:16) - to atone for possible impurity from hidden corpses

• the he-goat [of the additional offering] of Rosh Chodesh. -- to atone for entering the Mikdash or eating holy things in a state of impurity.

The Maskil LeDavid explains that Rashi is telling us that how we know that it was Rosh Chodesh offering that was not eaten. The term used is "לָשֵׂאת אֶת עֲוֹן הָעֵדָה" which is used only used in context with Tummat Kodshim.

He explains that when Rashi says only the Rosh Chodesh offering comes to atone, he is referring to an atonement for certain impurity (as implied by the wording in the verse, This excludes Nachshon's offering). [This seems to say that the Maskil LeDavid holds that Rashi differed with the Rambam and held that the Rosh Chodesh offering was an atonement for certain impurity, not possible impurity. - He says that Rashi implies this in his commentary to Zevachim 120, but a quick scan didn't show me what he was referring to.]

He concludes that while Rashi may seem to agree with this in Zevachim 120, it is tough to learn that that is what Rashi is saying here. This however, fits well with the Torat Kohanim's words.