Many types of korbanot (offerings) have a piece of them or a portion that is given over to the Kohanim (priests) to eat. They’re given to the Beit Av, the family of Kohanim who is doing the service in the Beit HaMikdash on that day. They’re given ownership of those meats, and they can eat them personally or share them with other Kohanim as well. We’ll talk about which Kohanim are entitled to that portion of the korbanot for that day in this Mishnah.
The Mishnah says tevul yom. A tevul yom is somebody who is tameh (ritually impure), who dipped in a mikveh (ritual bath), but he’s waiting for He’erev Shemesh. He’s waiting till nightfall. He could dip before nightfall, but he’s not allowed to partake of the korbanot or perform the avodah (service) until nightfall. So that type of person is a Kohen (priest). Mechusar Kippurim is also a Kohen who, because of the tumah (ritual impurity) that he’s experiencing—let’s say a zav (man with an abnormal discharge) or a metzora (person with a skin disease)—doesn’t only have to dip in a mikveh and wait until nightfall, but also has to bring a korban (offering) on that next day. So he lacks the atonement until he brings that korban. He’s not fully tahor (pure). While he may be allowed to eat terumah (priestly offering), he’s not allowed to do the avodah or eat from kodashim (sacred offerings).
So these types of individuals don’t partake of the offerings of that day by eating them that night, even though at night they technically would be fit to eat those korbanot. Since they weren’t fit to eat the korbanot or offer them at the point in time when they were offered, they’re not entitled to a share of the meat. Onen, somebody who experiences the death of a close relative on the day that the relative died, before burial, is an onen. They’re allowed to touch a korban, but they’re not allowed to actually offer it. Therefore, because they’re unfit to offer the korban, they don’t take a share of the meat to eat it that night, even though at night they technically would be fit to eat it.
A Kohen has a blemish, whether it’s permanent or temporary. They take a share of the korbanot and are allowed to eat them, but they’re not allowed to offer the korbanot. We say that the exception to the general rule we’ve had here is that a Kohen who is unfit to offer a korban does not share in the meat. There’s an exception to the rule here with a person who has a blemish. We learn this from the Pesukim (verses): the Ba’al Mum (person with a blemish) is still allowed to partake of the korban even though he cannot offer it. And here’s the general rule: any Kohen who’s not eligible to do the actual avodah does not take a share of the meat. And a Kohen who does not have a share in the meat does not share a portion of the skins of the hides as well. Even if he was tameh only when the blood of the korban was thrown on the Mizbeach (altar), but became pure when the fats were burnt on it, he does not take a share in the meat. The Pasuk (verse) tells us: “the one from Aharon’s sons who offers the blood of the shelamim (peace offerings) and the fat, the right thigh shall be his as a portion.” So we see from here that the crucial point in the avodah is the throwing of the blood. And a Kohen who was impure at that time does not take part in the korban. Even if he became pure later on, if he was impure when the blood was thrown, he does not take a portion of the korban.