Exodus 28:1; Exodus 38:21

1 And take thou unto thee Aaron thy brother, and his sons with him, from among the children of Israel, that he may minister unto me in the priest's office, even Aaron, Nadab and Abihu, Eleazar and Ithamar, Aaron's sons.

21 This is the sum of the tabernacle, even of the tabernacle of testimony, as it was counted, according to the commandment of Moses, for the service of the Levites, by the hand of Ithamar, son to Aaron the priest.