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.