Leviticus 21:4

Then Moses said to Aaron and to his sons Eleazar and Ithamar, “Do not uncover your heads nor tear your clothes, so that you will not die and that He will not become wrathful against all the congregation. But your relatives, the whole house of Israel, shall weep over the burning which Yahweh has brought about.

“But they shall not go to a dead person to make themselves unclean; however, for father, for mother, for son, for daughter, for brother, or for a sister who has not had a husband, they may make themselves unclean.