LEV 10:6

6 Then Moses/I said to Aaron and his [other two] sons Eleazar and Ithamar, “[You are sad because Nadab and Abihu died, but you must act like you always do]. Do not allow the hair on your [heads] to remain uncombed, and do not tear your clothes. But your relatives and all your fellow Israelis are allowed to mourn for those whom Yahweh destroyed by fire.