Numbers 19:7

5One shall burn the heifer in his sight; her skin, and her meat, and her blood, with her dung, shall he burn.

6The priest shall take cedar wood, hyssop, and scarlet, and cast it into the middle of the burning of the heifer.

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.

8He who burns her shall wash his clothes in water, and bathe his flesh in water, and shall be unclean until the evening.

9“A man who is clean shall gather up the ashes of the heifer, and lay them up outside of the camp in a clean place; and it shall be kept for the congregation of the children of Israel for use in water for cleansing impurity. It is a sin offering.