Abu Bakr as-Siddiq, also known as Abd Allah ibn Abi Quhafa, was a companion and father-in-law of the Prophet Muhammad. As one of the first people outside Muhammad's family to accept Islam, he was instrumental in spreading the faith among the people of Mecca. In 623 his daughter Aisha was married to Muhammad, strengthening the ties between the two men.
As a trusted advisor and close friend to Muhammad, and as a skilled general, Abu Bakr was an important authority figure in the uncertainty following Muhammad's death. Several of the companions urged him to take control as the first Caliph, but he was reluctant to do so at first, fearing that a hasty decision might cause divisions in the fledgling Ummah in future.
However, when a meeting was called at Saqifah to discuss the succession, Abu Bakr attended to try and keep the Ansar from coming to a premature decision. The other person with a strong claim, Muhammad's cousin Ali, was not expected to attend as he had insisted on completing the burial rites first. Nevertheless, it came as a great relief to many when Ali turned up after all, having been persuaded it was for the best, and Abu Bakr was one of the first to swear allegiance to Ali.
Later, it turned out that the man who had persuaded Ali was none other than the Emperor Heraclius, who had journeyed in disguise from Constantinople and accepted Islam after listening to Muhammad's Last Sermon. Heraclius, intending to try and convert the Roman Church to Islam, asked that Ali provide him with missionaries and theologians, and Abu Bakr was chosen to lead the mission. In 633 he was called before the Third Council of Constantinople to answer questions about his beliefs, and his testimony was enough to persuade many of the bishops to have Islam declared orthodox.
Afterwards, he returned to Egypt to continue his missionary work. He died in Pelusium on 23 August 634 and was returned to Medina for burial.