Leviticus 21:1-3

¹And the Lord said unto Moses, Speak unto the priests the sons of Aaron, and say unto them, None of them shall defile himself on the dead, among his people;

²But on his kin, that is near unto him, that is, on his mother, and on his father, and on his son, and on his daughter, and on his brother,

³And on his sister that is a virgin, that is nigh unto him, who hath had no husband: on her may he defile himself.