Leviticus 13:4-5, 23

But if the bright spot is white on the skin of his body, and does not appear to be deeper than the skin, and its hair has not turned white, then the priest shall isolate the one who has the sore seven days. And the priest shall examine him on the seventh day; and indeed if the sore appears to be as it was, and the sore has not spread on the skin, then the priest shall isolate him another seven days.

But if the bright spot stays in one place, and has not spread, it is the scar of the boil; and the priest shall pronounce him clean.