Abu Jafar Muhammad ibn Uthman
|The Fourteen Infallibles|
Abu Jafar Muhammad ibn Uthman was the second of The Four Deputies after death of Uthman ibn Sa’id al-Asadi, his father and the first deputy, in Twelver Shia Islam, who appointed as the agent and deputy of the twelfth and final Imam, Muhammad al-Mahdi, while he was in the Minor Occultation. He was Muhammad al-Mahdi's deputy until from 257 AH until his death in 304 0r 305 AH. He appointed after death of the first deputy. Abul Qasim Husayn ibn Ruh al-Nawbakhti was appointed as the third deputy of Muhammad al-Mahdi after the death of Ibn Uthman.
The kuniya and titles
Abu Jafar Muhammad ibn Utham has five titles: Amri, Asadi, Kufi, Sammaan (oil seller) and al-Askari. He is called Amri because of his grandfather's name was Amr and al-Asadi since he was from Banu Asad tribe. His Kunya is Abu Jafar. 
After the death of Uthman ibn Sa’id al-Asadi, the first deputy and the father of Abu Ja'far, he was appointed as the second deputy of Muhammad al-Mahdi. He performed ritual bathing of his father's body and burying him and received a letter of consolation ascribed to the Twelfth ImamMuhammad al-Mahdi at the death of Uthman ibn Sa'id. In Shia idea these acts are the unmistakable signs that Abu Ja'far was the successor of his father. Also before he became the deputy of twelfth Imam of Shia, he was trusted by Hasan al-Askari, the eleventh Imam of Shia. In a narration Hasan al-Askary noted to Abu Jafar as the representative of his son: "Bear witness that Uthman ibn Sa‘id Amri is my representative, and his son, Muhammad is representative of my son,Mahdi." He continued his father's activities ,delivered the letters and religious taxes the Shias gave to Muhammad al-Mahdi and critical activities against Bani Abbas. He remained the Muhammad al-Mahdi's deputy for almost fifty years and died in the year 304 AH. His grave is in East Baghdad.
His books in Ja'fari jurisprudence
According to Umm Kulthum, daughter of ibn Uthman:" Abu Ja’far Muhammad ibn Uthman has written books on Ja'fari jurisprudence in which he has collected all the traditions from Hasan al-Askari, Muhammad al-Mahdi and from his father Uthman ibn Sa'id who in turn has narrated from Ali al-Hadi. Among these books is one titled Al Ashrebah and according his will this book had reached to the third deputy Abul Qasim Husayn ibn Ruh al-Nawbakhti.
- Association of Imam Mahdi. Special Deputies.
- Muhammad Husayn Tabataba'i (1975). Shi'ite Islam. SUNY Press. p. 210.
- Jassim M. Hussain. The Occultation of the Twelfth Imam (A Historical Background). Muhammadi Trust of Great Britain and Northern Ireland.
- Mohammed Raza Dungersi. A Brief Biography of Imam Muhammad bin Hasan (a.s.): al-Mahdi. Bilal Muslim Mission. p. 20.
- Zahra Ra'isi. The Special Deputies of Imam Mahdi (as) (PDF). p. 79.
- Ebrahim Amini, Abdulaziz Sachedina. Al-Imam al-Mahdi, The Just Leader of Humanity. Ansariyan Publications - Qum.