Numbers 19:9-11

Now a man who is clean shall gather up the ashes of the heifer and put them outside the camp in a clean place, and the congregation of the sons of Israel shall keep them for water to remove impurity; it is purification from sin. And the one who gathers the ashes of the heifer shall wash his clothes and will be unclean until evening; and it shall be a permanent statute for the sons of Israel and for the stranger who resides among them. ‘The one who touches the dead body of any person will also be unclean for seven days.