Numbers 3:12, 15, 45

“Behold, I have taken the Levites from among the sons of Israel instead of and as a substitute for every firstborn, that is, the first that opens the womb among the Israelites. So the Levites shall be Mine

“Number the sons of Levi by their fathers’ households, by their families (clans). You shall number every male from a month old and upward.”

“Take the Levites [for Me] instead of all the firstborn among the sons of Israel, and the cattle of the Levites instead of their cattle. And the Levites shall be Mine. I am the LORD.