Numbers 3:12, 45

“Look, I have chosen the Levites from among the Israelites to serve as substitutes for all the firstborn sons of the people of Israel. The Levites belong to me

“Take the Levites as substitutes for the firstborn sons of the people of Israel. And take the livestock of the Levites as substitutes for the firstborn livestock of the people of Israel. The Levites belong to me; I am the LORD.