Numbers 19:7-8, 19

Then 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 even. And he that burneth her shall wash his clothes in water, and bathe his flesh in water, and shall be unclean until the even.

and the clean person shall sprinkle upon the unclean on the third day, and on the seventh day: and on the seventh day he shall purify himself, and wash his clothes, and bathe himself in water, and shall be clean at even.