Numbers 19:17-21

17For the purification of the unclean person, take some of the ashes of the burnt sin offering, put them in a jar, and pour fresh water1 over them. 18Then a man who is ceremonially clean is to take some hyssop, dip it in the water, and sprinkle the tent, all the furnishings, and the people who were there. He is also to sprinkle the one who touched a bone, a grave, or a person who has died or been slain.

19The man who is ceremonially clean is to sprinkle the unclean person on the third day and on the seventh day. After he purifies the unclean person on the seventh day, the one being cleansed must wash his clothes and bathe in water, and that evening he will be clean. 20But if a person who is unclean does not purify himself, he will be cut off from the assembly, because he has defiled the sanctuary of the LORD. The water of purification has not been sprinkled on him; he is unclean.

21This is a permanent statute for the people: The one who sprinkles the water of purification must wash his clothes, and whoever touches the water of purification will be unclean until evening.