Leviticus 21:1-6

The LORD said to Moses, “Tell these things to Aaron’s sons, the priests: ‘A priest must not make himself unclean by touching a dead person. But if the dead person was one of his close relatives, he may touch him. The priest may make himself unclean if the dead person is his mother or father, son or daughter, brother or unmarried sister who is close to him because she has no husband. The priest may make himself unclean for her if she dies. But a priest must not make himself unclean if the dead person was only related to him by marriage. “ ‘Priests must not shave their heads, or shave off the edges of their beards, or cut their bodies. They must be holy to their God and show respect for God’s name, because they present the offerings made by fire to the LORD, which is the food of their God. So they must be holy.