Leviticus 13:4-5, 23

But if the spot is white in the skin of his body and appears no deeper than the skin, and the hair in it has not turned white, the priest shall shut up the diseased person for seven days. And the priest shall examine him on the seventh day, and if in his eyes the disease is checked and the disease has not spread in the skin, then the priest shall shut him up for another seven days.

But if the spot remains in one place and does not spread, it is the scar of the boil, and the priest shall pronounce him clean.