Numbers 3:12, 15, 45

“Now, behold, I have taken the Levites from among the sons of Israel instead of every firstborn, the first issue of the womb among the sons of Israel. So the Levites shall be Mine.

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

“Take the Levites instead of all the firstborn among the sons of Israel and the cattle of the Levites. And the Levites shall be Mine; I am the LORD.