Midrash su Levitico 13:55

7) (Vayikra 13:55) ("And the Cohein shall see, after the plague-spot has been washed, and, behold, the plague-spot has not changed its appearance, and the plague-spot has not spread, it is unclean. In fire shall you burn it; it is p'cheteth in its karachath or in its gabachath.") "after the plague-spot has been washed, and, behold, the plague-spot has not changed its appearance and the plague-spot has not spread, it is unclean.": If it has not changed and not spread, it is tamei; but if it changed and did not spread, it should be examined as in the beginning. These are the words of R. Yehudah. And the sages say: It is tamei by reason of omed (viz. Vayikra 13:4 above). How, then, am I to understand "and, behold, it has not changed"? From any appearance that renders it subject to tumah (even if it changed from green to red).

8) "pcheteth": all of it appearing to be indented. — But perhaps only second-degree (dimness) is intended! — "It" ("It is pcheteth") indicates that it is as it was before. How, then, am I to understand "pcheteth"? As connoting (all of) it appearing to be indented.

9) "in its karachath": This refers to frayed (garments); "or in its gabachath": This refers to new (garments) — whence they ruled: sagus (a very thick cloak) on which a plague-spot appears — R. Eliezer b. Yaakov says: Until it appears in its weaving and its tufts.