שמות, פרק ט׳, פסוק ט׳

The plague of boils shifts the divine strikes into the realm of the air, following the earlier plagues that afflicted the water and the earth [ביאור יש״ר].

The formation of this plague involved an open miracle of volume and proportion. A tiny amount of kiln soot, which naturally should have scattered and vanished, miraculously multiplied. It expanded to cover the entire vast Egyptian empire while entirely sparing the Israelites [אבן עזרא, ביאור יש״ר, שטיינזלץ]. This event also turned the natural order upside down. Normally, ash is used to heal wounds, yet here it became the very source of a severe disease [צפנת פענח].

The primary approach among commentators is that this soot transformed into a dense cloud of dust, settling over Egypt like rain or dew. Winds carried the searing dust into every corner, penetrating even tightly closed homes so that no one could escape [רמב״ן, הטור הארוך, ביאור יש״ר]. Alternatively, some suggest that the idea of the soot becoming dust is simply a figure of speech meant to show how thoroughly it scattered [שד״ל]. Another perspective offers that the dust did not harm the people directly. Instead, God commanded a change in the very nature of the air, so that the air itself, wherever the dust was present, generated the sickness [רמב״ן, הטור הארוך].

The resulting disease was rooted in concepts of intense heat and dryness [רש״י, שד״ל, אם למקרא, ביאור יש״ר, קאסוטו]. It was a severe, burning skin affliction, recognized as a regional sickness in Egypt that would break out on its own. It was incredibly difficult to cure, though it was not fatal [שד״ל, קאסוטו]. The condition manifested as eruptions that protruded and spread across the entire body [רשב״ם, פרדס יוסף, קאסוטו]. Driven by the intense fever of the affliction, the skin broke out in blisters that bubbled up like boiling water or a flowing spring [אבן עזרא, שד״ל]. These blisters were filled with fluid and pus [רשב״ם, שפתי חכמים, ביאור יש״ר]. Ultimately, the affliction operated on two levels: it caused a severe internal dryness within the body, which then pushed outward to form the moist, infected blisters on the skin [העמק דבר, מלבי״ם, פרדס יוסף].