Numbers 19:9-10

9“‘Then a man who is ceremonially clean must gather up the ashes of the red heifer and put them in a ceremonially clean place outside the camp. They must be kept for the community of the Israelites for use in the water of purification – it is a purification for sin.

10The one who gathers the ashes of the heifer must wash his clothes and be ceremonially unclean until evening. This will be a permanent ordinance both for the Israelites and the resident foreigner who lives among them.