Leviticus 13:35-39

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. 38“When a man or woman has white spots on the skin,

39the priest is to examine them, and if the spots are dull white, it is a harmless rash that has broken out on the skin; they are clean.