Numbers 19:7-10

7Then the priest shall wash his clothes, and he shall bathe his flesh in water, and afterward he shall come into the camp, and the priest shall be unclean until the evening. 8And he that burneth her shall wash his clothes in water, and bathe his flesh in water, and shall be unclean until the evening. 9And a man that is clean shall gather the ashes of the heifer, and lay them outside the camp in a clean place, and it shall be kept for the congregation of the children of Israel for a water of separation: it is a purification for sin. 10And he that gathereth the ashes of the heifer shall wash his clothes, and be unclean until the evening: and it shall be to the children of Israel, and to the stranger that sojourneth among them, for a statute for ever.