Numbers 19:18-19

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.