Numbers 19:17-18

Then for the unclean person they shall take some of the ashes of the burnt purification from sin and running water shall be added to them in a container. And a clean person shall take hyssop and dip it in the water, and sprinkle it on the tent, on all the furnishings, on the persons who were there, and on the one who touched the bone or the one who was killed or the one who died naturally, or the grave.