Midrash su Levitico 13:48

1) (Vayikra 13:49) ("And it shall be, if the plague-spot is deep green or deep red in the garment or in the skin, or in the warp or in the woof, or in any article of skin, it is a plague-spot of leprosy, and it shall be shown to the Cohein.") Or perhaps just as (skin is likened to wool and) wool is from a small beast (a sheep), which is eaten, then skin, too, (to be subject to leprosy tumah) must be from a small beast, which is eaten. Whence do I derive (for inclusion) a small beast which is not eaten, a large beast which is eaten, a large beast which is not eaten … until I include the skins of sheratzim? From the repetition of "in the skin" (Vayikra 13:48 and Vayikra 13:49). I might think that both dyed and undyed skins are subject to tumah. It is, therefore, written (twice, Vayikra 13:48 and Vayikra 13:49) "garment." Just as "garment" connotes all white, so skins (to be subject to tumah) must be all white. These are the words of R. Meir. R. Yehudah says "or (in the skin") includes the dyed. R. Shimon says: One verse says "in the garment," (connoting white); another says "in the skin" (connoting also colored). How are these to be reconciled? Colored by Heaven are subject to tumah; colored by man are not subject to tumah.

4) (Vayikra 13:48) ("Or in the warp or in the woof of flax and of wool; or in skin, or in any worked skin.") I would exclude what is dyed by the hands of man, but I would not exclude what is dyed by the hands of Heaven; it is, therefore, written "of flax and of wool." Just as flax is white, so wool must be white (to be subject to plague-spot uncleanliness.)

5) "or in the warp or in the woof": I might think that the warp and woof of nafah and kevarah (types of sieves made from animal hair) were subject to (leprosy) tumah, (other varieties being excluded only if they do not qualify as "garment"); it is, therefore, written "in a garment of wool or in a garment of flax" (i.e., it is only a garment which acquires such tumah). I would then exclude (from such tumah) warp and woof of nafah and kevarah, but not that of (human) hair. And this would (also) follow a fortiori, viz. If wool, which in no instance is subject to burning because of tumah, (still) its warp and woof are subject to such tumah,