Numbers 3:1-4

11Now these are the records of the generations of Aaron and Moses at the time when the Lord spoke with Moses on Mount Sinai. 22These then are the names of the sons of Aaron: Nadab the firstborn, and Abihu, Eleazar and Ithamar. 3These are the names of the sons of Aaron, the 3anointed priests, whom he 4ordained to serve as priests. 45But Nadab and Abihu died before the Lord when they offered strange fire before the Lord in the wilderness of Sinai; and they had no children. So Eleazar and Ithamar served as priests 6in the lifetime of their father Aaron.