Leviticus 13:4-5, 23

“If there is a white spot on a person’s skin, but the spot does not seem deeper than the skin, and if the hair from the spot has not turned white, the priest must separate that person from other people for seven days. On the seventh day the priest must look at the person again. If he sees that the sore has not changed and it has not spread on the skin, the priest must keep the person separated for seven more days.

But if the bright spot does not spread or change, it is only the scar from the old boil. Then the priest must announce that the person is clean.