Numbers 3:3-5

New Revised Standard Version Catholic Edition

³ these are the names of the sons of Aaron, the anointed priests, whom he ordained to minister as priests. ⁴ Nadab and Abihu died before the Lord when they offered unholy fire before the Lord in the wilderness of Sinai, and they had no children. Eleazar and Ithamar served as priests in the lifetime of their father Aaron.

The Duties of the Levites

⁵ Then the Lord spoke to Moses, saying: