Leviticus 13:23

21But if the priest look on it, and, behold, there be no white hairs therein, and if it be not lower than the skin, but be somewhat dark; then the priest shall shut him up seven days:

22And if it spread much abroad in the skin, then the priest shall pronounce him unclean: it is a plague.

23But if the bright spot stay in his place, and spread not, it is a burning boil; and the priest shall pronounce him clean.

24Or if there be any flesh, in the skin whereof there is a hot burning, and the quick flesh that burneth have a white bright spot, somewhat reddish, or white;

25Then the priest shall look upon it: and, behold, if the hair in the bright spot be turned white, and it be in sight deeper than the skin; it is a leprosy broken out of the burning: wherefore the priest shall pronounce him unclean: it is the plague of leprosy.