Leviticus 13:24-28

24When there is a burn on someone’s skin and the raw area of the burn becomes reddish-white or white, 25the priest must examine it. If the hair in the spot has turned white and the spot appears to be deeper than the skin, it is a disease that has broken out in the burn. The priest must pronounce him unclean; it is a diseased infection.

26But if the priest examines it and there is no white hair in the spot, and it is not beneath the skin but has faded, the priest shall isolate him for seven days. 27On the seventh day the priest is to reexamine him, and if it has spread further on the skin, the priest must pronounce him unclean; it is a diseased infection. 28But if the spot is unchanged and has not spread on the skin but has faded, it is a swelling from the burn, and the priest is to pronounce him clean; for it is only the scar from the burn.