Mosaylima, or MOSEILEMA ('Little Moslem'), one of the most important rivals of Mohammed, belonged to the clan Dûl, a division of the tribe of the Beni Hanifah, of Yamâma in Nejd. The traditions about his life and age are extremely contradictory and legendary. It appears, however, tolerably certain that he had risen to some eminence in his tribe, probably as a religious teacher only at first, before Mohammed assumed his prophetic office. It was in the ninth year of the Hegira that Mosaylima, at the head of an embassy sent by his tribe, appeared before Mohammed, in order to settle certain points of dispute. Shortly after this event Mosaylima openly professed himself to be a prophet as well as Mohammed. The latter sent a messenger to him, as soon as he heard of this, to request him to reiterate publicly his profession of Islam. Mosaylima's answer was a request that Mohammed should share his power with him. 'From Mosaylima, the Apostle of God,' he is said to have written, 'to Mohammed, the Apostle of God. Now let the earth be half mine, and half thine.' Mohammed replied: 'From Mohammed, the Apostle of God, to Mosaylima, the liar. The earth is God's: He giveth the same for inheritance unto such of his servants as He pleases, and the happy issue shall attend those who fear Him.' Yet notwithstanding these testimonies, of probably late dates, it seems, on the other hand, perfectly certain that Mohammed made very great concessions to his rival—concessions that point to his having secretly nominated Mosaylima his successor, and that he by this means bought Mosaylima's open allegiance during his lifetime. It was not a question of dogmas, though they each had special revelations, but a question of supremacy which was thus settled amicably.
After Mohammed's death, in the 11th year of the Hegira, it at last came to an open breach between the two rival powers. Abu Bekr, the calif, sent Khalid, 'the Sword of the Faith,' with a number of choice troops, to compel Mosaylima to submission. Mosaylima awaited the enemy at Rowdah, a village in the Wadi Hanifah. So formidable indeed was Mosaylima's force that Khalid is said to have hesitated for a whole day and night. On the second morning, however, he advanced, and, in a battle which lasted until the evening, contrived, with fearful losses of his own, to gain the victory, in which Mosaylima fell, and his heresy was practically stamped out. It is extremely difficult to come to any clear notion of Mosaylima's real doctrines, as all the accounts that have survived of them come from victorious adversaries. See Sir W. Muir, Annals of the Early Caliphate (1883).