Leviticus 21:1-3

And the LORD said unto Moses, Speak unto the priests the sons of Aaron, and say unto them, There shall none be defiled for the dead among his people: But for his kin, that is near unto him, {that is}, for his mother, and for his father, and for his son, and for his daughter, and for his brother, And for his sister a virgin, that is nigh unto him, which hath had no husband; for her may he be defiled.