TSK · Numbers 26:61

Nadab and Abihu Then Aaron’s sons, Nadab and Abihu, each took his fire pan and put fire in it, set incense on it, and presented strange fire before the LORD, which he had not commanded them to do.

Nadab and Abihu died before the LORD when they offered strange fire before the LORD in the desert of Sinai, and they had no children. So Eleazar and Ithamar ministered as priests in the presence of Aaron their father.