Numbers 19:9; Numbers 19:17

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.

17 “For the unclean person, put some ashes from the burned purification offering into a jar and pour fresh water over them.