Bakr Muhammad died in 632 and the Muslims were in disagreement over who would succeed him as leader of their nascent community. On the same day of the Islamic prophet's death, the Ansar convened, in what became known as the Saqifah, and chose one of their own as caliph. Their principal aim was to prevent a Meccan, especially the new converts among the Qurayshite aristocracy, from gaining power over them. Opinion among the Muhajirun were split, with one side favoring a person closer to Muhammad in kinship, namely Ali, who they held was favored by Muhammad to succeed him. The other faction of the Muhajirun mostly backed Abu Bakr due to his seniority, closeness to Muhammad, and the increasingly important role he was attaining in the prophet's last years. The bulk of the Qurayshite new converts, with the prominent exception of Abu Sufyan, backed Abu Bakr. The Islamic tradition generally portrays Abu Bakr, Umar and Abu Ubayda as operating in concert and decisively intervening against the Ansar at Saqifah. After a debate, the triumvirate obtained the allegiance of the Ansarites to Abu Bakr despite their reservations. There are indications, according to the modern historian Elias Shoufani, that Umar initially favored Abu Ubayda as caliph, but that he lacked sufficient support against Abu Bakr, who he consequently supported against other potential candidates. A report in the history of al-Baladhuri holds that after Muhammad died, Umar told Abu Ubayda "Stretch your hand and let us give you the bay'ah [oath of allegiance], for you are the custodian (Amīn) of this ummah (the Muslim community), as the prophet called you". Abu Ubayda is then said to have declined in favor of Abu Bakr. Another report in the history of al-Tabari holds that Abu Bakr offered at Saqifah the caliphate to Umar or Abu Ubayda, but both insisted on Abu Bakr's succession. Commander in Syria Deployment and appointment to supreme command As the Ridda wars came to an end, Abu Bakr dispatched three or four armies at the same or different intervals toward Byzantine Syria to conquer that region. Though there are several versions in the early Islamic tradition, including in the works of Ibn Hubaysh al-Asadi (), al-Mas'udi (d. 956), al-Azdi (d. 944), as well as the 10th-century-compiled Kitab al-Aghani, that place Abu Ubayda as one of these commanders, modern research, including by historians H. A. R. Gibb, C. H. Becker, Philip K.