Leviticus 21:1-4

1Then the Lord said to Moses, “Speak to the priests, the sons of Aaron, and say to them:

‘1No one shall defile himself for a dead person among his people, 22except for his relatives who are nearest to him, his mother and his father and his son and his daughter and his brother, 3also for his virgin sister, who is near to him 3because she has had no husband; for her he may defile himself. 4He shall not defile himself as a 4relative by marriage among his people, and so profane himself.