Nadab and Abihu, however, died in the presence of the LORD when they offered unauthorized fire before the LORD in the Wilderness of Sinai. And since they had no sons, only Eleazar and Ithamar served as priests during the lifetime of their father Aaron.

Leviticus 10:1
Now Aaron's sons Nadab and Abihu took their censers, put fire in them and added incense, and offered unauthorized fire before the LORD, contrary to His command.

Leviticus 10:2
So fire came out from the presence of the LORD and consumed them, and they died in the presence of the LORD.

Numbers 3:5
Then the LORD said to Moses,

Numbers 19:3
Give it to Eleazar the priest, and he will have it brought outside the camp and slaughtered in his presence.

Numbers 20:25
Take Aaron and his son Eleazar and bring them up Mount Hor.

Numbers 26:61
but Nadab and Abihu died when they offered unauthorized fire before the LORD.

And 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: and Eleazar and Ithamar ministered in the priest's office in the sight of Aaron their father.