Leviticus 13:36

Then the priest shall look on him
Again, and which is no less than the fourth time; for notwithstanding his being pronounced clean, he was still subject to the inspection of the priest, if any alteration appeared: and, behold, if the scall be spread in the skin;
which was a certain sign of a leprosy: the priest shall not seek for yellow hair;
or be solicitous about that, whether there is any or not, for either one or the other of these signs were sufficient to determine the case: he [is] unclean;
and so to be pronounced.