משנה אויף ויקרא 21:2

If one has any kind of brother, [that brother] requires his brother’s wife to have yibbum, and he is his brother in every respect, except for a brother born from a female slave or a non-Jewish woman. If one has any kind of son, [that son] exempts his father’s wife from yibbum, and he is liable for striking or cursing [his father], and he is his son in every respect, except for the son of a female slave or a non-Jewish woman.

And who is the anointed priest? He who was anointed with the anointing oil and not he that has more garments. The only difference between a high priest who is anointed with the anointing oil and one who has more garments is the bull that is offered for [the unwitting transgression of] any of the commandments. And the only difference between the acting (high) priest and the former (high) priest is the bull on the Day of Atonement and the tenth part of the ephah. They are both equal in the service of the Day of Atonement, and both are commanded to marry a virgin and are forbidden to marry a widow; they are both forbidden to become impure for their relatives; they do not let their hair grow long, nor do they rend their clothes; and they return the (accidental) killer (from the city of refuge).

If one of [the two husbands] was an Israelite and the other a priest: He may only marry a woman who is eligible to marry a priest. He may not defile himself for the dead, but if he did defile himself he does not suffer the penalty of forty stripes. He may not eat terumah, but if he did eat he need not pay compensation either for the principal or [for the additional] fifth. He does not receive a share at the threshing-floor, but he may sell [his own] terumah and the profits are his. He receives no share in the holy things of the temple, no holy things are given to him, but he is not deprived of his own. He is exempt from [giving to any priest] the shoulder, the cheeks and the maw, while his firstling must remain in the pasture until it contracts a blemish. The restrictions relating to priests and the restrictions relating to Israelites are imposed upon him. If the two [husbands] were priests: He must be an onen mourner for them and they must be onenim mourners for him, but he may not defile himself for them, nor may they defile themselves for him. He may not inherit from them, but they may inherit from him. He is exempt if he strikes or curses the one or the other. He goes up [to serve] in the Temple watch of the one as well as of the other, but he does not receive a share [in the offerings]. If both served in the same watch, he receives a single portion.