Numbers 19:10-12

10And the one who gathers the ashes of the heifer 1shall 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.

11‘2The one who touches the dead body of any 3person will also be unclean for seven days. 12That one shall 4purify himself with 5the water on the third day and on the seventh day, and then he will be clean; but if he does not purify himself on the third day and on the seventh day, he will not be clean.