Leviticus 21:3-6

³and for his virgin sister who is near to him, who has had no husband; for her he may defile himself.

⁴He shall not defile himself, being a chief man amongst his people, to profane himself.

⁵“‘They shall not shave their heads or shave off the corners of their beards or make any cuttings in their flesh.

⁶They shall be holy to their God, and not profane the name of their God, for they offer the offerings of the LORD made by fire, the bread of their God. Therefore they shall be holy.