Ibn Ishaq, one of the earliest historians of Islam, in his book “Sirat Rasul Allah” (The Life of Muhammad, translated by A. Guillaume) does mention that measles and smallpox broke out in the same year that Abraha attacked, but there is no link between how Abraha was defeated and smallpox. According to Sira, as Abraha’s army withdrew, ” they were continually falling by the wayside dying miserably by every waterhole. Abraha was smitten in his body, and as they took him away his fingers fell off one by one. Where the fingers had been, there arose an evil sore exuding pus and blood, so that when they brought him to Sana he was like a fledgling. They allege that as he died his heart burst from his body. Deserters from the army, laborers and campfollowers in Mecca remained in Mecca and became workers and shepherds for the population.” The description hardly seems like that of smallpox in which there can be pus and pustules but usually fingers do not fall off. Secondly, it seems that the deserters from Abraha’s army did not suffer the same fate, which leads one to ask why decease would affect some and not others. Ishaq further mentions several poems that were written around the same time describing Abraha’s defeat. In one of these poems, Abu Qais b. al-Aslat al Ansari wrote that “God sent a wind bringing pebbles from above them.” He also wrote that “When the help of the Lord of the Throne reached you, His armies repulsed them, pelting them and covering them with dust.” Another poet Abdullah b. Qais al-Ruqqayat wrote, “Birds with pebbles hovered over them, so that they were as though they had been stoned.” Now, it is possible that a flock of birds accompanied and flew over a sandstorm, which is essentially a “blanket of wind-driven sand with an upper surface sometimes many feet (meters) above ground level.” That would explain the Quranic verses and the poems from that era perfectly.
Abraha: Was it Smallpox that Killed His Army?