Numbers 19:9-10

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.