Leviticus 13:29-33

29“When a man or woman has a plague on the head or on the chin,

30then the kohen is to examine the plague, and behold, if its appearance is deeper than the skin, and the hair in it is yellow and thin, then the kohen is to pronounce him unclean. It is a scab—tza'arat of the head or the chin.

31If the kohen examines the plague of the scab, and behold its appearance is no deeper than the skin and there is no black hair within, then the kohen is to isolate the person infected with the scab for seven days.

32On the seventh day the kohen is to examine the plague, and behold, if the scab has not spread and there is no yellow hair in it, and the appearance of the scab is no deeper than the skin,

33then he should be shaved, but he is not to shave the scab. The kohen is then to isolate the one who has the scab for seven more days.