Numbers 19:7-8

19:7 Then the priest must wash his clothes and bathe himself in water, and afterward he may come into the camp, but the priest will be ceremonially unclean until evening. 19:8 The one who burns it must wash his clothes in water and bathe himself in water. He will be ceremonially unclean until evening.

Numbers 19:10

19:10 The one who gathers the ashes of the heifer must wash his clothes and be ceremonially unclean until evening. This will be a permanent ordinance both for the Israelites and the resident foreigner who lives among them.