Kommentar zu Wajikra 13:18

שחין A BOIL — The word expresses the idea of heat. It is so called because the flesh has become inflamed by an injury which came about as the result of a blow and not as the result of fire (the latter case being mentioned in v. 24 and being termed a מכוה) (Chullin 8a).

שחין, our sages explained this as like the infected hot area of an injury on the flesh’s skin. There is another type of שחין, the result of a burning of the skin by fire.

Because of a wound. [This raises a strong difficulty: Why did Rashi not include an inflammation that came by itself and not because of a wound? (Re’m)] It seems Rashi’s intention is that so much more so [there is impurity regarding] an inflammation which occurred by itself and not because of a wound. Rashi only comes to exclude an inflammation that was caused by a fire, since that is called a מכוה (burn). All this is obvious in Toras Kohanim and Chulin (8a). Re’m brought the Gemora in Chulin and the Toras Kohanim but did not realize it is a kal vachomer, and therefore he wrote what he wrote (Nachalas Yaakov).

ונרפא, “and it is healed.” At first glance this word is enigmatic. How does this word get into this verse? However, we find that in the Torat Kohanim this word plus the fact that instead of the afflicted person being the subject in this verse, the subject is the state of his skin, teaches that in spite of the nega not being able to develop in the normal manner, the person so afflicted is already declared as ritually impure. The boil, שחין, must first heal completely, before a healing process for the nega can even begin.

ונרפא AND IT BECAME HEALED — the boil (not the flesh also mentioned in this verse) became healed and in its place it produced another plague (the שאת mentioned in the next verse).

The inflammation. [The inflammation healed] but not the flesh that had the inflammation, for you would not say the flesh “healed” as long as it has the שאת (spot of intense whiteness). Rather, it means the inflammation healed but the flesh is still afflicted.