Numbers 19:17-21

17For the purification of the unclean person, they are to take some of the ashes of the burnt sin offering, put them in a jar, and add fresh water to them.

18A person who is clean is to take 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, a corpse, or a person who had been killed.

19“The one who is clean is to sprinkle the unclean person on the third day and the seventh day. After he purifies the unclean person on the seventh day, the one being purified must wash his clothes and bathe in water, and he will be clean by evening.

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

21This is a permanent statute for them. The person who sprinkles the water for impurity is to wash his clothes, and whoever touches the water for impurity will be unclean until evening.