Numbers 8:21

And the Levites were purified
From sin, by the sprinkling of the sin water, or water of purification on them, ( Numbers 8:7 ) ; and they washed their clothes;
that they might have no defilement about them, neither in their bodies, nor in their garments: and Aaron offered them [as] an offering before the Lord;
a wave offering, as in ( Numbers 8:11 ) ; and Aaron made an atonement for them to cleanse them;
by offering the sacrifices for them, ( Numbers 8:12 ) .