Exodus 6:23

6:23 Aaron married Elisheba, the daughter of Amminadab and sister of Nahshon, and she bore him Nadab and Abihu, Eleazar and Ithamar.

Exodus 28:1

The Clothing of the Priests

28:1 “And you, bring near to you your brother Aaron and his sons with him from among the Israelites, so that they may minister as my priests – Aaron, Nadab and Abihu, Eleazar and Ithamar, Aaron’s sons.