Rashi on Leviticus 14:23/רש"י על ויקרא י״ד:כ״ג

1ביום השמיני לטהרתו ON TIIE EIGHTH DAY OF HIS BEING PRONOUNCED CLEAN — i. e. the eighth day after the birds have been brought and he has been sprinkled with the cedar stick, the hyssop and the crimson wool (cf. v. 10).