Leviticus 13:27-28

27On the seventh day the priest is to examine that person, and if it is spreading in the skin, the priest shall pronounce them unclean; it is a defiling skin disease.

28If, however, the spot is unchanged and has not spread in the skin but has faded, it is a swelling from the burn, and the priest shall pronounce them clean; it is only a scar from the burn.