Leviticus 21:3

1 And the Lord said to Moses, “Speak to the priests, the sons of Aaron, and say to them, No one shall make himself unclean for the dead among his people, 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.