Leviticus 13:21

But if the priest look on it
Upon a person in a like case as first described, having had a boil, and that healed, and afterwards a white swelling, or a bright spot in the place of it: and, behold, [there be] no white hairs therein;
not two hairs turned white, as Gersom interprets it: and [if] it [be] not lower than the skin;
the bright spot not lower than the skin; not having got into the flesh, only skin deep: the Targum of Jonathan is, not lower in whiteness than the skin; for the bright spot is described as white, and so the rising or swelling, ( Leviticus 13:19 ) ; but [be] somewhat dark;
or rather "contracted"; to which spreading is opposed in the next verse; (See Gill on Leviticus 13:6); then the priest shall shut him up seven days;
to wait and see whether it will spread or not: a boil and burning, the Jews say, make a man unclean in one week, and by two signs, the white hair, and the spreading; by the white hair, both at the beginning and at the end of the week after dismission, and by spreading at the end of the week after it ^F17.