An impostor who appeared in the time of Muhammad, and claimed the Prophetic office, surnamed Musailamatu ‘l-Kazzab, or, “Musailamah the Liar.” He headed an embassy sent by his tribe to Muhammad in the ninth year of the Hijrah, and professed himself a Muslim; but on his return home, considering that he might possibly share with Muhammad in his power, the next year he set up for a prophet also, pretending to join with him in the commission to recall mankind from idolatry to the worship of the true God; and be published written revelations, in imitation of the Qur’an, of which Abu ‘l-Faraj has preserved the following passage, viz. “Now hath God been gracious unto her that was with child, and hath brought forth from her the soul which runneth between the peritomoeum and the bowels.
Musailamah, having formed a considerable party, began to think himself upon equal terms with Muhammad, and sent him a letter, offering to go halves with him, in these words: “From Musailamah, the Apostle of God, to Muhammad, the Apostle of God. Now let the earth be half mine and half thine. But Muhammad, thinking himself too well established to need a partner, wrote him this answer: “From Muhammad, the Apostle of God, to Musailamah, the Liar. The earth is God’s; He giveth the same for inheritance unto such of His servants as He pleaseth; and the happy issue shall attend those who fear Him.”
During the few months which Muhammad lived after this revolt, Musailamah rather gained than lost ground, and grew very formidable; but Abu Bakr, in the eleventh year of the Hijrah, sent a great army against him, under the command of that consummate general Khalid ibn al-Walid, who engaged Musailamah in a bloody battle, wherein the false prophet happening to be slain by Wahshi, the negro slave who had killed Hamsah at Uhud, and by the same lance, the Muslims gained an entire victory, ten thousand of the apostates being left dead on the spot, and the rest returning to Islam.
Based on Hughes, Dictionary of Islam