Numbers 19:17

15Every open vessel, which has no covering bound on it, is unclean.

16“Whoever in the open field touches one who is slain with a sword, or a dead body, or a bone of a man, or a grave, shall be unclean seven days.

17“For the unclean, they shall take of the ashes of the burning of the sin offering; and running water shall be poured on them in a vessel.

18A clean person shall take hyssop, dip it in the water, and sprinkle it on the tent, on all the vessels, on the persons who were there, and on him who touched the bone, or the slain, or the dead, or the grave.

19The clean person shall sprinkle on the unclean on the third day, and on the seventh day. On the seventh day, he shall purify him. He shall wash his clothes and bathe himself in water, and shall be clean at evening.