Numbers 19:10-12

10The man who gathers up the ashes of the heifer must also wash his clothes, and he too will be unclean till evening. This will be a lasting ordinance both for the Israelites and for the foreigners residing among them.

11“Whoever touches a human corpse will be unclean for seven days.

12They must purify themselves with the water on the third day and on the seventh day; then they will be clean. But if they do not purify themselves on the third and seventh days, they will not be clean.