Numbers 19:4, 19

Next Eleazar the priest shall take some of its blood with his finger and sprinkle some of it toward the front of the Tent of Meeting (tabernacle) seven times.

Then the clean person shall sprinkle [the water for purification] on the unclean person on the third day and on the seventh day, and on the seventh day the unclean man shall purify himself, and wash his clothes and bathe himself in water, and shall be [ceremonially] clean at evening.