By this time the sinister tokens of physical decay, unavoidably betrayed by the Prophet, filled everyone with deepest concern. Abu Bekr observed him one day, stroking his beard and looking intently at it; then Abu, his eyes filling with sudden tears, broke out: “Ah, thou, for whom I would sacrifice father and mother, white hairs are hastening upon thee!” “Yes,” came the slow response, “it is the travail of inspiration that hath done this. The Suras Hud, and the Inevitable, and the Striking, with their fellows, these have made white my hair.” Yet when he actually became ill with pleurisy, or some sort of fever, he named a definite source for the malady: the poisoned mutton which Zeinab, the Jewess, had fed him. “This, verily, is the effect of that which I ate at Kheibar,” he declared. “The artery in my back feeleth as though it would just now burst asunder.” If his theory was correct, he doubtless died--as his worshipers fervently claimed--the honorable death of a martyr; but it seems probable that his illness had some more tangible origin. Believing that water could not be contaminated, he sometimes carelessly drank from a cistern that was used for slops; as a medicine man who had often attempted to cure his people by charms, cauterization and cupping, he had submitted himself to these practices so frequently that his system must have been gradually weakened; furthermore, Ayesha stated that his health had been poor for years, and that she had constantly dosed him with a profusion of odd concoctions which she herself compounded from innumerable prescriptions recommended by sympathizing friends.