The critics of Shiites and their Imams (a.s.) often object as to why Imam Ali Ibn Moosa al-Reza (a.s.) accepted to become the heir-apparent of the Abbaside Emperor Mamoon? Is this not opportunism? On the other hand, they also question that when Mamoon offered him the caliphate, why he (a.s.) refused? Do Shias not claim that Imamat and Caliphate is the right of the Imams (a.s.)?
A quick glance into history and the motives of this political move will clarify the matter for us. Is it logical for a person like Mamoon who killed his own brother for the post to give it up in favour of the opposition leader? Obviously, every wise person will realize this was a political stunt. Would the caliphate of the Imam (a.s.) not cause an uprising among the officers, governors and the rich who are habituated to oppression, plunder and suppression of the truth over a very long period of time? They would clearly not remain silent.
What a surprise to see the successor to Mansoor and Haroon trying to accord respect to the successor of the infallible guides, Imam Baqir (a.s.), Imam Sadiq (a.s.) and Imam Kazim (a.s.), all of whom were poisoned by such tyrants and despots from Umayyads and Abbasids.
The truth was far different. Mamoon wanted to defame Imam (a.s.). After Imam’s (a.s.) acceptance, he would foment disturbances through his accomplices, then return to the scene as a reformer and overthrow Imam (a.s.), claiming that divine caliphs do not possess the ability to lead the society.
But he was unaware that successor from the Prophet’s Household (a.s.) was aware of his nefarious intentions and was not willing to accept the caliphate.
Offer of Caliphate
Initially Mamoon offered Imam Reza (a.s.) caliphate saying that he (a.s.) was more eligible for it. On this, Imam (a.s.) retorted, “If Caliphate has been conferred on you by Allah, then you have no right to give it away. But if it does not belong to you, you have no right to confer it.”
Since Mamoon had no defense against this argument, he called upon Imam (a.s.) to accept the proposal of heir apparent (ولي عهد). Imam (a.s.) did not accept this proposal. But, Mamoon insisted to the point of compulsion and distress.
He now planned that giving Imam (a.s.) a place in his court would extinguish the flames of revolution, especially of the Alawi Saadaat. As a matter of fact, on seeing their representative in court, they would fall silent. Another probability would be that a few emotional people would look superficially into the problem without going to its bottom and form a wrong opinion of Shias and their leaders. They would disobey Imam (a.s.) under the excuse that he has joined hands with the unjust government. Then, either Imam (a.s.) would lose followers or silence them and it would be very easy to destroy him (a.s.). Mamoon would achieve absolute control over the entire Islamic nation.
Conditions for Acceptance
When Imam (a.s.) realized that there was no escape from accepting the offer, he put forth a seemingly simple condition:
My respected father (a.s.) informed me that I will depart from this world before you. I will martyred through poison. Angels will cry upon me. I will be buried in a state of being distant from my home and buried next to Haroon. Hence, I will not interfere with current affairs like appointment and dismissal of governors, political and military affairs.
As Mamoon had become impressed by Imam’s (a.s.) acceptance, he readily accepted the condition without realizing that this was indication enough that the acceptance was under duress. It was meaningless that he accepts being the heir but stays away from official government work.
Imam Reza’s (a.s.) supplication
Thereafter, Imam (a.s.) raised his head towards the sky and supplicated:
O Allah! You know that I am compelled to accept this position of heir-apparent. Don’t hold me responsible for it just as you did not hold Your Prophets (a.s.) – Yusuf and Danial (a.s.) – when they both were forced to accept such positions by the kings of their time.” (Behar al-Anwar v 49, p 131, trad 7 from Oyoon Akhbar al-Reza (a.s) v 1 p 18)
Anyhow, the agreement written personally by Mamoon was sent to Imam (a.s.). Imam (a.s.) too wrote something behind it and quoted a verse in the third sentence:
یَعْلَمُ خَائِنَةَ الْاَعْیُنِ وَمَا تُخْفِی الصُّدُوْرُ.
He knows the stealthy looks and that which the breasts conceal.
Writing of the verse was a clear indication that Imam (a.s.) was aware of Mamoon’s treachery. Finally the settlement took place and Imam (a.s.) was placed as heir apparent in Marv.
It was not long before Mamoon realized his defeat. The revolutionary movements had not subsided and Imam (a.s.) was still ruling the hearts of people.
- Imam Reza (a.s.) was forced to accept the position of heir-apparent
- Mamoon’s aim was to crush the uprisings of the Shiites in different areas and send a message that their leader was with him
- He (a.s.) wanted to show the people that Imam Reza (a.s.) was after worldly power. Needless to state, he failed in all his evil aims.
Finally, he decided to kill Imam (a.s.). On the 17th day of Safar, 203 Hijri, he poisoned Imam Reza (a.s.) and left a permanent shameful stain of pure blood on his clothes by this cowardly act, thereby becoming eligible for an eternal painful punishment in the hell-fire. (Waseelah al-Najaat, p. 381)
It is also possible that he offered the heir apparent position with the intent of eventually killing Imam Reza (a.s.) so the needle of suspicion would never point in his direction seeing how he was close to Imam (a.s.) and even offered him caliphate and heir apparent. This is further validated by the fact that Mamoon observed a fake mourning period to commemorate Imam’s (a.s.) martyrdom to ward off suspicion.
 Surah Ghaafir (40), Verse 19