Numbers 19:10-12

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.

11“Whoever touches any dead body will be unclean for seven days.

12He is to purify himself on the third day and on the seventh day. Then he will be clean. But if he does not purify himself on the third and seventh days, he will not be clean.