Numbers 8:16
For they are entirely given to me from among the Israelites. I have taken them for myself instead of all who open the womb, the firstborn sons of all the Israelites.
Numbers 3:12
"Look, I myself have taken the Levites from among the Israelites instead of every firstborn who opens the womb among the Israelites. So the Levites belong to me,
Numbers 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.
Numbers 3:9
You are to assign the Levites to Aaron and his sons; they will be assigned exclusively to him out of all the Israelites.