Numbers 19:4, 19

Next Eleazar the priest shall take some of its blood with his finger and sprinkle some of its blood toward the front of the tent of meeting seven times.

Then the clean person shall sprinkle on the unclean on the third day and on the seventh day; and on the seventh day he shall purify him from uncleanness, and he shall wash his clothes and bathe himself in water and shall be clean by evening.