Leviticus 21:1-4

1Then Adonai said to Moses, “Speak to the kohanim, the sons of Aaron, and say to them: A kohen is not to allow himself to become unclean for the dead among his people,

2except for his relatives that are nearest to him—his mother, his father, his son, his daughter, his brother,

3or his virgin sister who is near to him, who has had no husband. For her he may allow himself to become unclean.

4But he is not to defile himself—a husband among his people—and so profane himself.