Numbers 19:7-8, 19

“Then the priest must wash his clothes and bathe himself in water. Afterward he may return to the camp, though he will remain ceremonially unclean until evening. The man who burns the animal must also wash his clothes and bathe himself in water, and he, too, will remain unclean until evening.

On the third and seventh days the person who is ceremonially clean must sprinkle the water on those who are defiled. Then on the seventh day the people being cleansed must wash their clothes and bathe themselves, and that evening they will be cleansed of their defilement.