NUM 19:18

18 Then someone who is still acceptable to me must take a stalk of [a plant named] hyssop and dip it into the water. Then that person must sprinkle some of the water on the tent where that person died, on the things that are in the tent, and on the people who were in the tent. He must also sprinkle some of that water on any person who touched a human bone or who touched a person who died, or who touched a grave.