Exodus 34:20
You must redeem the firstborn of a donkey with a lamb; but if you do not redeem it, break its neck. You must redeem all the firstborn of your sons. No one shall appear before Me empty-handed.

Numbers 3:12
"Behold, I have taken the Levites from among the children of Israel in place of every firstborn Israelite from the womb. The Levites belong to Me,

Numbers 3:41
You are to take the Levites for Me--I am the LORD--in place of all the firstborn of Israel, and the livestock of the Levites in place of all the firstborn of the livestock of the Israelites."

Numbers 3:44
Again the LORD spoke to Moses, saying,

Numbers 8:16
For the Levites have been wholly given to Me from among the sons of Israel. I have taken them for Myself in place of all who come first from the womb, the firstborn of all the sons of Israel.

Numbers 18:6
Behold, I Myself have selected your fellow Levites from the Israelites as a gift to you, dedicated to the LORD to perform the service for the Tent of Meeting.

Malachi 2:4
Then you will know that I have sent you this commandment, that My covenant with Levi may continue," says the LORD of Hosts.