Leviticus 21:1-3

¹The LORD said to Moses, “Speak to the priests, the sons of Aaron, and say to them, ‘A priest shall not defile himself for the dead amongst his people,

²except for his relatives that are near to him: for his mother, for his father, for his son, for his daughter, for his brother,

³and for his virgin sister who is near to him, who has had no husband; for her he may defile himself.