Numbers 19:17-21

17Then for the unclean person they shall take some of the ashes of the heifer burnt for the purification from sin, and running water shall be added to them in a container.

18A clean person shall take hyssop and dip it in the water and sprinkle it on the tent and on all the furnishings and on the people who were there, and on the one who touched the bone or the one who was killed or the one who died [naturally] or the grave.

19Then the clean person shall sprinkle [the water for purification] on the unclean person on the third day and on the seventh day, and on the seventh day the unclean man shall purify himself, and wash his clothes and bathe himself in water, and shall be [ceremonially] clean at evening.

20‘But the man who is unclean and does not purify himself, that person shall be cut off from among the assembly, because he has defiled the sanctuary of the Lord. The water for purification has not been sprinkled on him; he is unclean.

21So it shall be a perpetual statute to them. He who sprinkles the water for impurity [on another] shall wash his clothes, and he who touches the water for impurity shall be unclean until evening.