Numbers 8:15 WEB

¹³  You shall set the Levites before Aaron, and before his sons, and offer them as a wave offering to Yahweh.

¹⁴  Thus you shall separate the Levites from among the children of Israel, and the Levites shall be mine.

¹⁵  'After that, the Levites shall go in to do the service of the Tent of Meeting: and you shall cleanse them, and offer them as a wave offering.

¹⁶  For they are wholly given to me from among the children of Israel; instead of all who open the womb, even the firstborn of all the children of Israel, I have taken them to me.

¹⁷  For all the firstborn among the children of Israel are mine, both man and animal. On the day that I struck all the firstborn in the land of Egypt, I sanctified them for myself.