Midrash su Levitico 13:27

6) (Vayikra 13:22) ("And if it spreads, spreads, in the skin, the Cohein shall declare him tamei; it is plague.") "spreads, spreads, in the skin": What is the intent of this? Because it is written (Vayikra 13:27) "And the Cohein shall see him on the seventh day, if it spreads, spreads, in the skin," I might think that a spreading renders him unclean only on the seventh day. Whence do I derive the same for the eighth, ninth, and tenth day? From (the redundant) "spread, spread."

8) (Vayikra 13:27) "And the Cohein shall see him on the seventh day. If it has spread, spread, in the skin, etc." I might think that a spreading confers tumah only at the end of a week. Whence do I derive (that it does so) even after exemption? From (the redundant) "spread, spread."

9) If he were confirmed through white hair, and the white hair disappeared and then returned; and, similarly, through a spreading: at first inspection, at the end of a week, after exemption — where he was confirmed through a spreading and the spreading disappeared and then returned — and, similarly, through white hair, at the end of a week and after exemption — in respect to all of these instances, it is written (the redundant) "if it has spread, spread." Why is "leprosy" written three times (in respect to "a burn," (once here and twice in 13:25)? "leprosy" — It requires the size of a garis (a Cilician bean); "leprosy" — to render what is stated in respect to a se'eth applicable to a bahereth, and what is stated in respect to a bahereth applicable to a se'eth; "leprosy" — to render what is stated in respect to a boil applicable to a burn, and what is stated in respect to a burn applicable to a boil. Why is "it" written three times (once here and twice in 13:25)? "it" — it (a burn, unlike a skin plague-spot) is not rendered tamei by the eruption of a michyah, at first inspection, at the end of a week (of quarantine), and after exemption. "it" — to exclude the spreading of bohak (white scurf) at the end of a week or after exemption. "it" — it has no fifth shade (aside from the four indicated). (And a fourth possible derivation:) "it" — boil and burn do not combine with each other.