Numbers 19:7-10

7After that, the priest must wash his clothes and bathe himself with water. He may then come into the camp, but he will be ceremonially unclean till evening. 8The man who burns it must also wash his clothes and bathe with water, and he too will be unclean till evening. 9“A man who is clean shall gather up the ashes of the heifer and put them in a ceremonially clean place outside the camp. They are to be kept by the Israelite community for use in the water of cleansing; it is for purification from sin. 10The man who gathers up the ashes of the heifer must also wash his clothes, and he too will be unclean till evening. This will be a lasting ordinance both for the Israelites and for the foreigners residing among them.