Hisham, by the help of his personal talent, bravery and special boldness, used to stand against the opponents of Wilayah and Imamate and defend the Prophet's chaste household without any fear and anxiety. It was because of this obstinacy and intrepidity that the caliph had decided several times to kill him and at last due to anxiety, fear and serious heart trouble, Hisham sacrificed his life.
Among his bold debates, there is a story which is quoted by Allamah Mohsen Amin as follows:
One day, Yahya ibn Khaled Barmaki, the minister, asked Hisham in the presence of the caliph Haroon al Rashid - Tell us, is it possible that a right cause happens to face opposition from two sides and that the beliefs of two persons who are quite different to each other (like two poles) may be right or that both of their opinions may be correct?
Hisham: It is impossible.
Yahya: If two persons have different opinions regarding one and the same religious matter, is it possible that both of them may be right or both of them wrong?
Hisham: The reply of this question is also clear according to the previous answer. It is not possible that both parties may be right. This sort of thing is impossible and certainly one of them may be right and the other wrong.
Yahya: (to put Hisham in an awkward position and provoke the wrath of Haroon he said) So, O' Hisham, when Ali ibn Abi Taleb and Abbas1 ibn Abdul Mutallib had disputes about the inheritance of the post of caliphate, and put the arbitration before Abubakr*: Who was right and who was wrong.
Hisham (He thought to himself that if he would say that Ali was in the wrong, he would become an infidel and would have exceeded the bounds of religion. If he would say that Abbas's claim was futile and he was in the wrong, then Haroon would order immediately to kill him. This was an unusual problem and till that day this type of discussion had not happened and he had no ready answer for this question before hand.)
Hisham thought of the sayings of Imam Al-Sadiq (a) who used to say: "Till you defend our cause by the help of your speech, you will be favoured by the Holy Spirit." So I became hopeful and understood that I would not be condemned, insulted or defeated. Suddenly a reply occurred to me I said: Neither Ali (a) nor Abbas was mistaken and neither of them was in the wrong. Rather both of them were right and their difference was not an actual difference and they had no conflict between themselves, but apparently it seemed like that. Their story is just like those two angels of the heaven who are mentioned in the Qur'an and they took their dispute to Hazrat Dawood (a). So which angel was right and which one had made a mistake? Or would you say that both of them were wrong? Whatever would be your answer regarding that matter; my answer would be the same regarding Ali (a) and Abbas.
Yahya: In my opinion, neither of these angels made a mistake rather both of these angels were right. In fact, they had no dispute and the exposition of their difference was only to attract the attention of Hazrat Dawood (a) and to let him know of the Decree of God.
Hisham: Therefore, I would say regarding Ali (a) and Abbas that they had no dispute concerning the matter of caliphate and in fact both of them were of one and the same opinion. Their retelling of the dispute was only to inform the caliph (Abubakr) about his mistake and their action was similar to the action of those angels.
Yahya gave no answer at all. He was looking at Haroon amazed and ashamed. The caliph who was very much impressed by Hisham's attractive speech, applauded and praised him.