Numbers 19:4

19:4 Eleazar the priest is to take some of its blood with his finger, and sprinkle some of the blood seven times directly in front of the tent of meeting.

Numbers 19:19

19:19 And the clean person must sprinkle the unclean on the third day and on the seventh day; and on the seventh day he must purify him, and then he must wash his clothes, and bathe in water, and he will be clean in the evening.