Numbers 19:19-20

19The clean person will sprinkle the unclean one on the third and seventh days. He is to purify himself on the seventh day, and on the seventh day he is to wash his clothes and bathe himself in water, and at evening he will be clean.

20However, that man who is unclean but does not purify himself will be cut off from the community. He has defiled the Sanctuary of Adonai, since the cleansing water was not sprinkled on him. He is unclean.