Midrash su Levitico 13:14

1) (Vayikra 13:14) ("And on the day that there appears in it living flesh he shall be unclean.") We are hereby taught about limb tips that are revealed (in the midst of the blossoming, the nega having departed from them) that they are tamei, (their having become like living flesh in a bahereth). I might think (that this obtains with) any amount (of revelation); it is, therefore, written here "living flesh," and above (Vayikra 13:10, in respect to michyah) "living flesh." Just as "healthy flesh" mentioned there must be (at least the size of a lentil), here, too, it must be a lentil. These are the words of R. Yossi. R. Meir says: Is he rendered tamei by reason of michyah? Did (we not learn [viz. Chapter 2:9]) that michyah does not confer tumah through limb tips? Rather, this is "a decree of the King," and tumah is (conferred through) any amount. R. Yossi countered: Is he rendered tamei by reason of limb tips? Is he not tamei even if (the living flesh) returns to its middle? It is written here "living flesh," and there, "living flesh." Just as "living flesh" there is lentil-size, so "living flesh" here is lentil-size.

2) "And on the day": We are hereby (by this redundancy) taught that he (a groom) is given two (types of days [the seven days of the marriage feast and those of a festival]) for (non-inspection of plague-spots): for (those of) his body, for (those of) his house, and for those of his garments. These are the words of R. Yehudah. Rebbi says (that a special verse is not required for this, for) it is written (Vayikra 14:36): "And the Cohein shall command, (and they shall empty out the house before the Cohein comes in to see the plague-spot, so that there not be made unclean all that is in the house.") If they wait for a mundane matter, shall they not wait for a matter of mitzvah! And how much (i.e., how many days) is his mitzvah? For a groom we allow the seven days of the marriage feast, for himself, his house, and his garments. And thus on a festival — we allow him all the days of the festival.

3) ("And on the day there appears in it living flesh he shall be unclean.") What is the intent of "it"? Whence do you derive that if it blossomed in all of him, but not in the head, the beard, the boil, the burn, and the "rebellious" blister, and the head and the beard became bald, and the boil and the burn and the blister became scarred — I might think that he were tamei, all of the above now being regarded as "impeding" his complete whiteness), it is, therefore, (to negate this) written "it," the blossoming. If there appears in it (living flesh), he is tamei; but if the head and the beard became bald, and the boil and the burn and the blister (became scarred), he is not tamei (but tahor).