Numbers 19:10-12

10The man who has gathered up the ashes of the heifer must also wash his clothes, and he will be ceremonially unclean until evening. This is a permanent statute for the Israelites and for the foreigner residing among them.

11Whoever touches any dead body will be unclean for seven days. 12He must purify himself with the water 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.