Numbers 19:9-10

“Then a man who is ritually clean will gather the ashes of the cow and place them in a ritually clean place outside the camp. The congregation of Israel will keep them to use in the Water-of-Cleansing, an Absolution-Offering. “The man who gathered up the ashes must scrub his clothes; he is ritually unclean until evening. This is to be a standing rule for both native-born Israelites and foreigners living among them.