Muhammad Abu Ja’far, the brother of Imam al-Askari (a.s.), was a wonderful example of the infallible imams and a true picture of their thoughts and principles. He was very intelligent, with high morals and possessed vast knowledge, to the extent that many of the Shi’a thought that he would be the Imam after his father Imam al-Hadi (a.s.).
Al-Aarif al-Kilani said about Abu Ja’far, ‘I accompanied Abu Ja’far Muhammad bin Ali since he was young. I saw no one purer nor more honorable than him. Abul Hasan al-Askari (Imam al-Hadi) left him in Hijaz while he was a child and then he came to him a young. He kept to his brother Abu Muhammad (a.s.) who educated him and fed him with his knowledge, wisdom, and morals.’
Abu Ja’far became seriously ill, maybe because of being poisoned by the Abbasids. He remained in this state for some days, suffering intolerable pains while his brother Imam Abu Muhammad (a.s.), who loved him much, was with him all this time. However, after not long, Abu Ja’far departed to the better world, but Imam Abu Muhammad’s heart was broken and he was very sorrowful and distressed over the loss of his dear brother.