Aaron’s sons Nadab and Abihu put coals of fire in their incense burners and sprinkled incense over them. In this way, they disobeyed the Lord by burning before him the wrong kind of fire, different than he had commanded.So fire blazed forth from the Lord’s presence and burned them up, and they died there before the Lord.
But Nadab and Abihu died in the Lord’s presence in the wilderness of Sinai when they burned before the Lord the wrong kind of fire, different than he had commanded. Since they had no sons, this left only Eleazar and Ithamar to serve as priests with their father, Aaron.
This is how Aaron’s descendants, the priests, were divided into groups for service. The sons of Aaron were Nadab, Abihu, Eleazar, and Ithamar.But Nadab and Abihu died before their father, and they had no sons. So only Eleazar and Ithamar were left to carry on as priests.