Leviticus 13:34-37

34On the seventh day the priest is to examine the sore, and if it has not spread in the skin and appears to be no more than skin deep, the priest shall pronounce them clean. They must wash their clothes, and they will be clean. 35But if the sore does spread in the skin after they are pronounced clean, 36the priest is to examine them, and if he finds that the sore has spread in the skin, he does not need to look for yellow hair; they are unclean. 37If, however, the sore is unchanged so far as the priest can see, and if black hair has grown in it, the affected person is healed. They are clean, and the priest shall pronounce them clean.