Numbers 19:9-10

9“A clean man is to gather up the ashes of the heifer and put them in a clean place outside the camp. They are to be for the community of Bnei-Yisrael to use as water of purification from sin.

10“The one who gathers the heifer’s ashes is also to wash his clothes as well as be unclean until evening. It will be a permanent statute for Bnei-Yisrael and for the outsider living among them.