Numbers 3:4-6

Holman Christian Standard Bible

⁴ But Nadab and Abihu died in the Lord’s presence when they presented unauthorized fire^(A) before the Lord in the Wilderness of Sinai, and they had no sons. So Eleazar and Ithamar served as priests under the direction of Aaron their father.^(B)

⁵ The Lord spoke to Moses: ⁶ “Bring the tribe of Levi near and present them to Aaron the priest to assist him.