Leviticus 13:30-34

then the priest shall look at the infection, and if it appears to be deeper than the skin and there is thin yellowish hair in it, then the priest shall pronounce him unclean; it is a scale, it is leprosy of the head or of the beard.

But if the priest looks at the infection of the scale, and indeed, it appears to be no deeper than the skin and there is no black hair in it, then the priest shall isolate the person with the scaly infection for seven days.

And on the seventh day the priest shall look at the infection, and if the scale has not spread and no yellowish hair has grown in it, and the appearance of the scale is no deeper than the skin,

then he shall shave himself, but he shall not shave the scale; and the priest shall isolate the person with the scale for seven more days.

Then on the seventh day the priest shall look at the scale, and if the scale has not spread in the skin and it appears to be no deeper than the skin, the priest shall pronounce him clean; and he shall wash his clothes and be clean.