Numbers 19:19-20

And the clean person must sprinkle the unclean on the third day and on the seventh day; and on the seventh day he must purify him, and then he must wash his clothes, and bathe in water, and he will be clean in the evening. But the man who is unclean and does not purify himself, that person must be cut off from among the community, because he has polluted the sanctuary of the LORD; the water of purification was not sprinkled on him, so he is unclean.