Midrash su Levitico 13:13

2) "if it be": from the pronouncement on (see Section 1:2). "in a man": to include the plague-spot appearing in all of the man — that the michyah makes him tamei (i.e., even though if all of the man turned white he is tahor (viz. Vayikra 13:13), still, if there is a michyah in the plague-spot, he is tamei because of the michyah.) Now (why is a verse needed to tell me this?) does it not follow a fortiori? viz.: If a michyah causes tumah in a small bahereth (the size of a garis), how much more so does it cause tumah in a large bahereth (which covers his entire body! — No, this may be true of a small bahereth, which is a sign of tumah. Would you then say the same for a large bahereth, which is not a sign of tumah! Since it is not a sign of tumah, (we would say that) a michyah should not cause tumah in it. It must, therefore, be written "in a man," to include a plague-spot appearing in all of the man — that the michyah makes him tamei.

5) (Vayikra 13:13) ("And the Cohein shall see, and, behold, the leprosy has covered all of his flesh, then he shall declare the plague-spot clean; all of it has turned white — it is clean.") "And the Cohein shall see, and, behold, the leprosy has covered": What is the intent of this? I might think that the blossoming (in all of his flesh) renders him clean only in a se'eth. Whence is the same derived for the other (three) appearances? From "and the leprosy has covered." "all of his flesh": to include in between the fingers of his hands and his feet. Variantly: What is the intent of "all of his flesh"? Whence do you derive that if it blossomed in all of him but not in a half-lentil size near the head, the beard, the boil, the burn and the blister, and then it returned to the head and the beard, and they became bald — the boil and the burn and the blister, and they became scarred — I might think that he would be tahor. It is, therefore, written "all of his flesh" — it must blossom in all of him (for him to be tahor).

6) "then he shall declare the plague-spot clean … it is clean": What is the intent of this? I might think that blossoming renders clean only after confirmation of michyah in the beginning (i.e., at the first inspection, as per the verse). Whence do I derive the same for confirmation of michyah at the end of the first week (of quarantine), at the end of the second week; after confirmation of white hair in the beginning, at the end of the first week, at the end of the second week, after exemption (at the end of the second week by reason of its remaining the same in appearance); after confirmation of spreading at the end of the first week, at the end of the second week, after exemption; and blossoming (in all of him) after quarantine? (Whence do you derive that blossoming renders all of these clean?) From "then he shall declare the plague-spot clean … it is clean." — to include all (of the above instances).