Leviticus 13:21-23

21But if the priest look on it, and behold, there are no white hairs therein, and it is not deeper than the skin, and is pale, the priest shall shut him up seven days;

22and if it spread much in the skin, then the priest shall pronounce him unclean: it is the sore.

23But if the bright spot have remained in its place, [and] have not spread, it is the scar of the boil; and the priest shall pronounce him clean.