Text 6
A sin-offering and a guilt-offering may be brought only for a sin. They may not be brought because of a pledge or a vow. [Hence,] if one says: "I promise to bring a sin-offering" or "...a guilt-offering," his statements are of no consequence.
Rambam, Laws of Sacrifices 14:8
As the law explains, a person may not simply vow to bring a sin offering. A sin offering can only be brought on account of an actual transgression, and when there is none, his oath to bring such a sacrifice is meaningless.
However, though one may not bring a sin offering as a random pledge, he may do so to atone for another person’s sin. This second point is presented in the continuation of the law:
Text 7
[When] one says: "I promise to bring the sin-offering, burnt-offering, guilt-offering, and peace-offering of so-and-so." If that person agrees, he may allow him to bring those sacrifices for him and he [that person] receives atonement thereby.
Rambam, Laws of Sacrifices 14:10
This idea of one individual being able to bring a sacrifice for another reveals two innovative points:
1) From the perspective of the laws of making an oath:
When a person declares, “I promise to bring a sin offering...” his pledges are of no consequence, as there exists no standing obligation to bring the offering. However, in a situation where the individual says, "I promise to bring the sin-offering...of so-and-so," being that for this second individual an obligation for the sacrifice does exist, the person’s oath is valid, and he is thereby required to bring the offering on account of this pledge.
2) From the perspective of atonement:
Even though the obligation to bring the sacrifice falls only on the person who sinned or is in need of atonement, the Torah nevertheless makes a revolutionary ruling that one individual can bring atonement for another individual’s sin. Since every Jew is a guarantor for his fellow, he can therefore bring a sacrifice in his friend’s stead, and affect atonement for his friend’s sin!
This concept finds its source in the Talmud:
Text 8
All Israel are guarantors one for another.
Talmud, Shavuos 39a
Because every individual Jew is responsible for his fellow, he has the ability to bring a sacrifice that will actually atone for his fellow’s sin.
