Numbers 19:19-20

19A person who is clean will sprinkle these types of unclean people on the third day and the seventh day. On the seventh day the clean person will finish taking away their sins. Then they must wash their clothes and bodies, and in the evening they will be clean.

20But if the person who becomes unclean doesn’t have his sin taken away, that person must be excluded from the assembly. He has made the holy place of the Lord unclean. The water to take away uncleanness wasn’t sprinkled on him. He is unclean.