Numbers 8:16 in the King James Version
For they are wholly given unto me from among the children of Israel; instead of such as open every womb, even instead of the firstborn of all the children of Israel, have I taken them unto me.
Context
15 “After that, the Levites shall go in to do the service of the Tent of Meeting. 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.