Leviticus 21:5

2 except for his closest relatives, his mother, his father, his son, his daughter, his brother, 3 or his virgin sister (who is near to him because she has had no husband; for her he may make himself unclean). 4 He shall not make himself unclean as a husband among his people and so profane himself.

5 They shall not make bald patches on their heads, nor shave off the edges of their beards, nor make any cuts on their body. 6 They shall be holy to their God and not profane the name of their God. For they offer the Lord’s food offerings, the bread of their God; therefore they shall be holy.

7 They shall not marry a prostitute or a woman who has been defiled, neither shall they marry a woman divorced from her husband, for the priest is holy to his God. 8 You shall sanctify him, for he offers the bread of your God. He shall be holy to you, for I, the Lord, who sanctify you, am holy.