Abu Shu'ayb Muhammad ibn Nusayr, was a disciple of the tenth Twelver Shi'a Imam, Ali al Hadi and of the eleventh Imam, Hasan al Askari (d. 873). Ibn Nusayr was known to his companions as a representative (Bab) of al-Askari and of the twelfth Imam, Muhammad al-Mahdi during the Minor Occultation. A rival of his in claiming to be the Bab (door) to the Imams was Abu Yaqub Ishaq, founder of the Ishaqiyya.