Numbers 3:4

Overview - Numbers 3
1	The sons of Aaron.
5	The Levites are given to the priests instead of the first-born;
14	are numbered by their families.
21	The families, number, and charge of the Gershonites;
27	of the Kohathites;
33	of the Merarites.
38	The place and charge of Moses and Aaron.
40	The first-born are freed by the Levites.
44	The overplus are redeemed.

Numbers 3:4  (King James Version)
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.