Abubekr, the first caliph, born at Mecca about 573, died in 634. Abubekr means "father of the virgin," and this name was given to him when his daughter Ayesha became the favorite wife of Mohammed. His real name was Abd-el-Caaba. He was Mohammed's most trusted adherent, and in 632 succeeded his master in the supreme authority, to the exclusion of the prophet's son-in-law Ali. At the commencement his reign was troubled, first by the relapse of several tribes to idolatry, and then by the springing up of a new sect under Mosseilama. Assisted by the hero Khaled, Abubekr compelled the backsliders to return, and suppressed the rival creed, Mosseilama himself being slain in a battle. He now led his followers to conquest. His generals fell upon the frontiers of the Roman and Persian empires, and their easy success excited the warrior population of Arabia to pour forth. The emperor Ileraclius vainly opposed them. Syria and the provinces of the Euphrates were soon overrun and Damascus besieged. Abubekr died in the full tide of conquest, after a brief reign of two years and three months.

His tomb is shown by the side of that of the prophet at Mecca. Abubekr was surnamed the Just. His charity was unbounded, while his manner of living was so strict that he possessed at his death only the one robe he wore, one camel, and an Ethiopian slave. These he bequeathed to Omar, his successor. Abubekr collected the scattered writings and the oral doctrines of Mohammed forming the Koran.