Números 3:4

4 Nadab and Abihu, however, died before the Lord when they made an offering with unauthorized fire before him in the Desert of Sinai. They had no sons, so Eleazar and Ithamar served as priests during the lifetime of their father Aaron.

4 And Nadab and Abihu were put to death before the Lord when they made an offering of strange fire before the Lord, in the waste land of Sinai, and they had no children: and Eleazar and Ithamar did the work of priests before Aaron their father.