Numbers 3:12, 15, 45

“Now behold, I Myself have taken the Levites from among the children of Israel instead of every firstborn who opens the womb among the children of Israel. Therefore the Levites shall be Mine

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

“Take the Levites instead of all the firstborn among the children of Israel, and the livestock of the Levites instead of their livestock. The Levites shall be Mine: I am the LORD.