Leviticus 21:1-5

1Then the Lord said to Moses, “Speak to the priests, the sons of Aaron, and say to them: ‘No one shall defile himself [that is, become ceremonially unclean] for the dead among his people [by touching a corpse or assisting in preparing it for burial],

2except for his relatives who are nearest to him, his mother, his father, his son, his daughter, and his brother,

3also his virgin sister, who is near to him because she has had no husband; for her he may become unclean.

4He shall not become unclean as a relative by marriage among his people, and so profane himself.

5The priests shall not shave their heads, nor shave off the edges of their beards, nor make any cuts in their body.