And the 89th mitzvah is that the kohanim are commanded to eat the meat of the sacrifices, i.e., the sin-offering and guilt-offering, which are kodshei kadashim.1

The source of this commandment is G‑d's statement2 (exalted be He), "They shall eat [those offerings] which are brought for atonement."

In the words of the Sifra: "What verse teaches us that the consumption of the sacrifices achieves atonement for the entire Jewish people? The verse,3 'It has been given to you to remove the community's guilt and atone for them before G‑d.' How is this done? The kohanim eat and the non-kohanim thereby receive atonement."

One of the conditions of this commandment is that the mitzvah of eating [the sacrifice] applies only on the day [on which the sacrifice was brought] and the following night until midnight.4 The eating is considered a mitzvah only during the proper time period, and consuming that sin-offering or guilt-offering afterwards is prohibited.

It is clear that this mitzvah also applies only to male kohanim and not to females, since women may not eat the sacrifices that are mentioned in this mitzvah — i.e., kodshei kadashim.

The other category of sacrifices, known as kodshim kalim, however, [differ in both respects]. In general, they may be eaten for two days, including the night in between. The exceptions to this rule are the thanksgiving-offering and the ram offered by a nazir which, although in this category, still may be eaten only for one day and the following night. In addition, women are allowed to partake of kodshim kalim, and their [kodshim kalim] consumption is also considered a mitzvah.

Consumption of terumah is also considered a mitzvah. However, consumption of kodshim kalim and of terumah are not on the same level as the consumption of the sin-offering and the guilt-offering. This is because only the consumption of the latter offerings brings atonement, as explained above, and the actual commandment was said only in reference to them. There is no explicit mention, however, of the consumption of terumah or kodshim kalim. They are therefore included in this mitzvah [rather than counting as separate mitzvos5], and one who consumes them is considered to have fulfilled a mitzvah.6

[We see one who consumes terumah is considered to have fulfilled a mitzvah from] the words of the Sifra:7 "The verse8 'I am giving your priesthood as a gift' comes to compare the consumption of terumah9 in all Eretz Yisrael to the service in the Temple: just as washing the hands must precede the Temple service, so too it must precede the consumption of terumah in Eretz Yisrael."

The details of this mitzvah are explained in a number of passages in tractate Zevachim.