Note 175 — Chapter XI · CAMPAIGN IN SYRIA.—BATTLE OF WACUSA ON THE YERMUK. A.H. XIII. A.D. 634.
Reading edition
The date is fixed by that of Abu Bekr’s death (August 22); twenty days after which we are told that the battle was fought. But the messenger bringing the news of the Caliph’s death could hardly have taken more than half that time for so urgent a journey. We may safely, therefore, place the action about the end of August (Jumâd II.); or, rather, following other traditions, early in Rajab, that is, the beginning of September.