Muhammad al-Mahdi is believed by Twelver Shia Muslims to be the last of the Twelve Imams and the Mahdi, who will emerge in the End of Times to establish justice and will be assisted by Jesus. Following the death of the eleventh Imam Hasan al-Askari in 873, his chief representative Uthman ibn Sa'id al-Asadi reported that the eleventh Imam had an infant son named Muhammad, who had been kept hidden from the public out of fear of Abbasid persecution and had entered occultation. Representatives of al-Askari supported these assertions, while Shia Muslims fragmented into several sects over al-Askari's succession. All of these sects either disappeared within a few decades or were eventually absorbed into the mainstream Twelver Shia Islam, whose adherents recognized al-Askari's son as the final Imam and the Mahdi, who entered occultation and remains alive until his eventual reappearance.