Numbers 3:41-45

3:41 And take the Levites for me – I am the Lord – instead of all the firstborn males among the Israelites, and the livestock of the Levites instead of all the firstborn of the livestock of the Israelites.” 3:42 So Moses numbered all the firstborn males among the Israelites, as the Lord had commanded him. 3:43 And all the firstborn males, by the number of the names from a month old and upward, totaled 22,273.

3:44 Then the Lord spoke to Moses: 3:45 “Take the Levites instead of all the firstborn males among the Israelites, and the livestock of the Levites instead of their livestock. And the Levites will be mine. I am the Lord.