He had written a book called “al-Bisharaat”.Isaaq bin Muhammad al-Basri narrated that Muhammad bin Ibrahim bin Mahziyar said to him, ‘When my father (Ibrahim) was about to die, he gave me some money and gave me a certain sign. No one knew about this sign except Allah the Almighty. He said to me, ‘Whoever shows you this sign, you have to give him this money.’ I went to Baghdad and stopped at an inn. On the following day, someone came and knocked the door. I asked the servant to see who he was. The servant said, ‘An old man at the door.’ I said, ‘Let him come in.’ The old man came in, took a seat and said, ‘I am al-Umari. Give me the money that is with you which is so- and-so.’ He showed me the sign and I gave him the money.’Al- Umari was the agent of Imam Abu Muhammad (a.s.).Ibrahim bin Mahzi- yar narrated from Imam Abul Hasan al-Hadi (a.s.), Imam Abu Muhammad al-Askari (a.s.), Ibn Abu Umayr, and others. Ahmad bin Muhammad, Sa’d bin Abdullah, Abdullah bin Ja’far al-Himyari, and others narrated from him.