Numbers 19:19-20

Then the clean person shall sprinkle on the unclean on the third day and on the seventh day; and on the seventh day he shall purify him, and he shall wash his clothes and bathe himself in water and will be clean by evening. ‘But the person who is unclean and does not purify himself, that person shall be cut off from the midst of the assembly, because he has defiled the sanctuary of the LORD; the water for impurity has not been sprinkled on him, so he is unclean.