14In this way you shall separate the Levites from the rest of the Israelites, and the Levites will belong to Me.
15After you have cleansed them and presented them as a wave offering, they may come to serve at the Tent of Meeting.
16For the Levites have been wholly given to Me from among the sons of Israel. I have taken them for Myself in place of all who come first from the womb, the firstborn of all the sons of Israel.
— Numbers 8:14-16