Numbers 3:2-4

New Century Version

² Aaron had four sons: Nadab, the oldest, Abihu, Eleazar, and Ithamar. ³ These were the names of Aaron’s sons, who were appointed to serve as priests. ⁴ But Nadab and Abihu died in the presence of the Lord when they offered the wrong kind of fire before the Lord in the Desert of Sinai. They had no sons. So Eleazar and Ithamar served as priests during the lifetime of their father Aaron.