Leviticus 13:29-31

29And if a man or a woman have a sore on the head or on the beard,

30and the priest look on the sore, and behold, it looketh deeper than the skin, and there is in it yellow thin hair, then the priest shall pronounce him unclean; it is a scall, the leprosy of the head or the beard.

31And if the priest look on the sore of the scall, and behold, it is not in sight deeper than the skin, and there is no black hair in it, the priest shall shut up [him that hath] the sore of the scall seven days.