Midrash su Levitico 13:26

5) (Vayikra 13:21) "And if the Cohein see it" — all in one sighting. "and, behold, there is no white hair in it" — not in it (the boil), but not in a strand projecting from it (i.e., if there were white hair in the strand, it is tahor). I might think (that the strand was not considered part of the boil) even if there were in it the breadth of two hairs; it is, therefore, written ([Vayikra 13:26] in respect to a burn) "and, behold, there is not in the bahereth white hair" (connoting that any significant projection [i.e., the breadth of two hairs] is considered part of the bahereth).

6) (Vayikra 13:26) "And if the Cohein see it," (all in one sighting). "and there is not in the bahereth white hair": As they have said: This includes (as being considered part of the burn) a strand, the breadth of two hairs, that projects from it.

7) "and it is not lower than the skin and it is dim": As they have said: This includes (an appearance that is) level (with the skin) or higher.