Hesham, who was never defeated in debates, was a universal champion and his fame spread every where. He was always victorious over his opponents in every debate. Every one was anxious to witness his debates. Haroon, the most powerful caliph of the time, who was to a certain extent among the opponents, was also more anxious than others to watch the discussion and the speech of Hesham.
So one day, he ordered Yahya ibn Khaled, his minister to arrange a meeting and put Hesham face to face with Abdullah ibn Yazid Abazi, the chief of the Kharajites, who was also one of the famous learned men of the time. The caliph also sat in a secret place behind the curtain in such a manner that he was able to listen to their discussions clearly but they could not see him.
Then the caliph ordered Yahya ibn Khaled Barmaki to ask Abdullah to put forth his questions to Hesham. Yahya, by the order of Haroon, turned his face to Abdullah and said: "Put forth your questions to Aba Muhammad, Hesham." Hesham (by taking this opportunity) said: "The Khawarej have no right to ask us about anything."
Abdullah -Why is this so?
Hesham - Because you were the people who first believed as we did in the justice of the man (i.e. Amirul Mu'mineen Ali [a], his Imamate and virtue, and then separated yourself from us and initiated intrigues and enmity with him. As we still have the same belief, so your first faith and agreement is a proof for us; your later opposition and enmity does not harm us and your arrogation is not accepted as an injury to us. This is so because the contradiction made after acceptance is not effective, your witnessing as an enemy of mine is acceptable if it is useful to me as your enemy. But if it is harmful to me as your enemy it is unacceptable.
Yahya ibn Khaled - O Hesham, you have almost defeated Abdullah and have brought him to the verge of defeat at the edge of a cliff. However, treat him moderately, as the caliph wants you to continue the discussion with him (although he did not hint at all that the caliph was present behind the curtain).
Hesham - I am ready for debate, but there is a difficult point. The point is that it may be possible that our discussion may be lengthy and reach a place where there may occur some problems and complications and both of us may not accept the reality due to obstinacy, enmity and the critical nature of the topic. If it is advisable then appoint someone as a judge between us so that he may he able to make us return at the time of our deviation from the right path.
Abdullah - By God, Abu Muhammad (Hesham) has suggested a just proposal.
Hesham - Now, that it is time to appoint a referee; who should be this referee and a follower of which religion? Should he be one of my supporters or one of your friends? Should he oppose both of our beliefs or be opposed to the Muslim community and Islam?
Abdullah - You should select anyone whom you like, because you are a just man and I am satisfied with your selection.
Hesham - In my opinion it is a difficult task because if that judge comes from among my supporters then you will not be safe from his party spirit; and if he comes from among your supporters then I may not be safe. On the contrary, if he is from among the opponents and against both of our beliefs, then none of us may be safe from the harm of his unjustified arbitration. Then it is advisable that one man from each side oversees our speech; and witnesses our discussion and debate and arbitrates according to justice and fairness.
Abdullah - Very well, it is a just suggestion and I was also expecting the same from you.
Then, Hesham turned his face towards Yahya and said: "O Vizir (minister) be a witness that I have disapproved of his reasoning and have condemned him and have made him helpless. He has nothing to say anymore and I also do not need to debate with him."
Haroon shook the curtain and said to Yahya: "What does this Shia (Mutakallem) theologian say? He is still discussing with Abdullah about the rules and regulations, and the introduction of the topic. He has not yet started the actual debate. How he is claiming that he has condemned him and discarded his religion? Ask Hesham to prove his claim."
Yahya turned his face towards Hesham and said: "Amirul Mu'mineen (Haroon) orders you to prove the truth of your claim and explain how have you condemned this learned man and nullified the Kharajite sect?
Hesham - Is it not true that in the beginning these Kharajites were of the same opinion as we were concerning the matter of Imamate and the Wilayah of Amirul Mu'mineen [a], until the problem of the arbitration occurred in the Battle of Siffin? They acted rudely and shamelessly towards Amirul Mu'mineen [a] and called him an infidel because of the acceptance of the arbitration although they themselves compelled him (Hazrat) to accept this matter. Now this learned man who is himself respectable and reliable among his followers, has accepted the arbitration and judgement of the two men without any compulsion and force - one of these two men is my follower who is an infidel according to his Khawarijite belief and the other is his own supporter. Both of them have different beliefs and are opposed to each other. Now if he is right in choosing the arbitration and has chosen the right path, then there is no cause for him to criticize Amirul Mu'mineen [a] who is more worthy and wise. And if he has made a mistake then he is himself an infidel and his wickedness does not harm us. He has given evidence of his own infidelity. So first it is most necessary to check out his infidelity and his faith, enabling us to see whether he is himself an infidel or a Muslim. This is necessary before checking his opinion regarding the matter of the infidelity of Ali [a].
When the discussion of Hesham reached this point, Haroon became uneasy because of the clear reasoning and knockout proofs of Hesham. But he was so enchanted by his speech that he involuntarily applauded him and ordered to give him a reward. It is to be noted that Hesham was skilful in the practical sciences, and it is a fact that his discussions and speeches have been completely based upon intellectual, philosophical and theological reasoning in addition, as we noticed in the above story, he has used his own particular technique and has defeated his opponents.
 In some books, the name of the father of Abdullah has been recorded as Zayd, which is apparently wrong.
 Kharajites area group of people who were at first the followers of Imam Ali [a] and Shias. Then at the Battle of Siffin, due to the insistence of the army, the problem of arbitration occured. According to this, one person from Mu'awiyah's side and one person from Imam Ali's [a] side should be appointed and whatever they announced, all other people should obey their decision. Contrary to the desire of Amirul Mu'minin, Abu Musa Ashary was appointed from Ali's side and Amr As from Mu'awiyah's side was appointed for this purpose. After some time Amr As cheated him cleverly and cunningly and the story ended in favour of Mu'awiyah. As a result of this trickery a group came out as opponents against Ali [a] and said: Ali [a], because you accepted the arbitration of Mu'awiyah and Amr As who were infidels, we do not accept you anymore. Their slogan was: "There is no verdict except that of Allah." At last Ibn Muljim, who was one of them, killed Ali [a].