Numbers 19:7-10

7Then the priest shall wash his clothes and bathe his body in water, and afterward he may come into the camp. But the priest shall be unclean until evening. 8The one who burns the heifer shall wash his clothes in water and bathe his body in water and shall be unclean until evening. 9And a man who is clean shall gather up the ashes of the heifer and deposit them outside the camp in a clean place. And they shall be kept for the water for impurity for the congregation of the people of Israel; it is a sin offering. 10And the one who gathers the ashes of the heifer shall wash his clothes and be unclean until evening. And this shall be a perpetual statute for the people of Israel, and for the stranger who sojourns among them.