Numbers 3:39-41

Living Bible

³⁹ So all the Levites, as numbered by Moses and Aaron at the command of the Lord, were 22,000 males one month old and older.

⁴⁰ Then the Lord said to Moses, “Now take a census of all the eldest sons in Israel who are one month old and older, and register each name. ⁴¹ The Levites shall be mine (I am Jehovah) as substitutes for the eldest sons of Israel; and the Levites’ cattle are mine as substitutes for the firstborn cattle of the whole nation.”