Leviticus 13:18-20

18And the flesh — when in the skin thereof cometh a boil, and it is healed,

19and there is in the place of the boil a white rising, or a white-reddish bright spot, it shall be shewn to the priest;

20and the priest shall look on it, and behold, it looketh deeper than the skin, and the hair thereof is turned white; then the priest shall pronounce him unclean: it is the sore of leprosy broken out in the boil.