and you shall gird them, Aaron and his sons, with sashes and tie headdresses on them, and the priesthood shall be theirs by a perpetual ordinance. You shall then ordain Aaron and his sons.
Moses spoke to Aaron and to his remaining sons, Eleazar and Ithamar, “Take the grain offering that is left from the Lord’s offerings by fire, and eat it unleavened beside the altar, for it is most holy;
But you and your sons with you shall diligently perform your priestly duties in all that concerns the altar and the area behind the curtain. I give your priesthood as a gift; any outsider who approaches shall be put to death.”
Nadab and Abihu died before the Lord when they offered unholy fire before the Lord in the wilderness of Sinai, and they had no children. Eleazar and Ithamar served as priests in the lifetime of their father Aaron.