Leviticus 21:1-3

¹Yahweh also said to Moses/me, “Speak to the priests, the sons of Aaron, and say to them,

²‘You priests must not cause yourselves to become unfit to do my work by touching corpses. Priests are permitted to touch only the corpses of close relatives, such as the priest's mother or father or his son or daughter or his brother.

³Priests are also permitted to touch the corpse of a sister if she is not married, because she has no husband to bury her body.