Numbers 19:16-18, 20-21

And if someone in an open field touches the corpse of someone who was killed with a sword or who died a natural death, or if someone touches a human bone or a grave, that person will be defiled for seven days. “To remove the defilement, put some of the ashes from the burnt purification offering in a jar, and pour fresh water over them. Then someone who is ceremonially clean must take a hyssop branch and dip it into the water. That person must sprinkle the water on the tent, on all the furnishings in the tent, and on the people who were in the tent; also on the person who touched a human bone, or touched someone who was killed or who died naturally, or touched a grave.

“But those who become defiled and do not purify themselves will be cut off from the community, for they have defiled the sanctuary of the LORD. Since the water of purification has not been sprinkled on them, they remain defiled. This is a permanent law for the people. Those who sprinkle the water of purification must afterward wash their clothes, and anyone who then touches the water used for purification will remain defiled until evening.