Leviticus 21:1-6

The LORD said to Moses, “Give the following instructions to the priests, the descendants of Aaron. “A priest must not make himself ceremonially unclean by touching the dead body of a relative. The only exceptions are his closest relatives—his mother or father, son or daughter, brother, or his virgin sister who depends on him because she has no husband. But a priest must not defile himself and make himself unclean for someone who is related to him only by marriage. “The priests must not shave their heads or trim their beards or cut their bodies. They must be set apart as holy to their God and must never bring shame on the name of God. They must be holy, for they are the ones who present the special gifts to the LORD, gifts of food for their God.