Numbers 19:7-8, 21

Then the priest shall wash his clothes and bathe his body in water, and afterward he may come into the camp. But the priest shall be unclean until evening. The one who burns the heifer shall wash his clothes in water and bathe his body in water and shall be unclean until evening.

And it shall be a statute forever for them. The one who sprinkles the water for impurity shall wash his clothes, and the one who touches the water for impurity shall be unclean until evening.