So went Satan forth from the presence of the LORD, and smote Job with sore boils from the sole of his foot unto his crown. Sore boils - בשחין רע bischin ra, "with an evil inflammation." What this diabolical disorder was, interpreters are not agreed. Some think it was the leprosy, and this is the reason why he dwelt by himself, and had his habitation in an unclean place, without the city, (Septuagint, εξω της πωλεως), or in the open air: and the reason why his friends beheld him afar off, Job 2:12, was because they knew that the disorder was infectious.
His scraping himself with a potsherd indicates a disease accompanied with intolerable itching, one of the characteristics of the smallpox. Query, Was it not this disorder? And in order to save his life (for that he had in especial command) did not Satan himself direct him to the cool regimen, without which, humanly speaking, the disease must have proved fatal? In the elephantiasis and leprosy there is, properly speaking, no boil or detached inflammation, or swelling, but one uniform disordered state of the whole surface, so that the whole body is covered with loathsome scales, and the skin appears like that of the elephant, thick and wrinkled, from which appearance the disorder has its name. In the smallpox it is different; each pock or pustule is a separate inflammation, tending to suppuration; and during this process, the fever is in general very high, and the anguish and distress of the patient intolerable. When the suppuration is pretty far advanced, the itching is extreme; and the hands are often obliged to be confined to prevent the patient from literally tearing his own flesh.