And the LORD said unto Moses, "Speak unto the priests the sons of Aaron and say unto them, 'A priest shall defile himself at the death of none of his people, but upon his kin that is nigh unto him: as his mother, father, son, daughter and brother: and on his sister as long as she is a maid and dwelleth nigh him and was never given to man: on her he may defile himself. read more.
But he shall not make himself unclean upon a ruler of his people to pollute himself withal. They shall make them no baldness upon their heads or shave off the locks of their beards, nor make any marks in their flesh. They shall be holy unto their God, and not pollute the name of their God, for the sacrifices of the LORD and the bread of their God they do offer: therefore they must be holy.

neither shall go to any dead body nor make himself unclean: no not on his father or mother, neither shall go out of the sanctuary, that he pollute not the holy place of his God, for the crown of the anointing oil of God, is upon him. I am the LORD.