Numbers 19:7-10

7Then the priest must wash his clothes and bathe his body in water; after that he may enter the camp, but he will remain ceremonially unclean until evening.

8The one who burned the cow must also wash his clothes and bathe his body in water, and he will remain unclean until evening.

9“A man who is clean is to gather up the cow’s ashes and deposit them outside the camp in a ceremonially clean place. The ashes will be kept by the Israelite community for preparing the water to remove impurity; it is a sin offering.

10Then the one who gathers up the cow’s ashes must wash his clothes, and he will remain unclean until evening. This is a permanent statute for the Israelites and for the alien who resides among them.