Numbers 8:15 ASV

¹³  And thou shalt set the Levites before Aaron, and before his sons, and offer them for a wave-offering unto Jehovah.

¹⁴  Thus shalt thou separate the Levites from among the children of Israel; and the Levites shall be mine.

¹⁵  And after that shall the Levites go in to do the service of the tent of meeting: and thou shalt cleanse them, and offer them for a wave-offering.

¹⁶  For they are wholly given unto me from among the children of Israel; instead of all that openeth the womb, even the first-born of all the children of Israel, have I taken them unto me.

¹⁷  For all the first-born among the children of Israel are mine, both man and beast: on the day that I smote all the first-born in the land of Egypt I sanctified them for myself.