Al-Ma'mun held a general popular festival attended by the ministers, the high-ranking statesmen, the commanders of the armed forces, and the rest of the people; at their head were the 'Alawides and the 'Abba`sids; the festival was held on Tuesday, the second day of the blessed month of Ramadan , in the year 201.
Al-Ma'mu`n was seated and he had had two great cushions placed for Ima`m al-Rida`, so that he would have the same kind of seat and covers. He seated al-Rida`, peace be on him, on them; he was dressed in green and wearing a turban and a sword. Then al-Ma'mu`n ordered his son, al-'Abba`s, to be the first of the people to make the pledge of allegiance to him , and then the people pledged allegiance to him.

The Way of the Pledge of Allegiance
As for the way the people followed to pledge allegiance to the Ima`m, peace be on him, it was unique, with which the Umayyad and the 'Abba`sid kings were not familiar, for he, peace be on him, moved his hand and hit his own face with the back of it and their faces with the palm. "Stretch out your hand for the pledge of allegiance," al-Ma'mu`n demanded.
"The Apostle of Allah, may Allah bless him and his family, used to make the pledge in this way when the people pledge allegiance to him," retorted al-Rida, peace be on him.
Perhaps the Ima`m depended on these words of Him, the Exalted: "The hand of Allah is above their hands." So it was not permissible for one who made the pledge of allegiance to place his own hand above the hand of the Prophet, may Allah bless him and his family, or above the hand of the Ima`m, peace be on him.

The Imam predicts that this Matter will not be achieved
Imam al-Rida, peace be on him, was dressed in the robes of honor and attended that meeting. Orators and poets rose and began to mention his great merit and summoned the people to pledge allegiance to him. The Ima`m, peace be on him, looked at one of his close associates, who was feeling happy about what had happened. He signaled him to come closer. He went closer to him, and he said so that no one else could hear: "Do not occupy your heart with this matter and do not be happy about it. It is something which will not be achieved."
The matter was as the Ima`m, peace be on him, had said, for this pledge of allegiance to him was not achieved, and al-Ma'mu`n broke his promise when he gave him poison to drink and assassinated him.

Al-Ma'mun delivers a Speech
When the ceremonies of the pledge of allegiance to the Ima`m were over, al-Ma'mu`n rose, ascended the pulpit, and addressed the people, saying: "O people, you have come to know about the pledge of allegiance to 'Ali b. Mu`sa` b. Ja'far b. Mohammed b. 'Ali b. al-Husayn b. 'Ali b. Abu` Ta`lib, peace be on him. By Allah, if I recited these names before the deaf and the dumb, they would recover with the permission of Allah, the Great and Almighty."

Imam al-Reza(A.S.) delivers a Speech
After the pledge of allegiance to Ima`m al-Rida`, peace be on him, had terminated, al-Ma'mu`n asked him to ascend the pulpit and address the people, so he went up on the pulpit. He praise and glorified Allah, and then he said: "O People, we have a right due to us from you through the Messenger of Allah, may Allah bless him and his family, and you also have a right due to you from us through him. If you carry out your duty to us, then it is necessary for us to carry out our duty to you."
The Ima`m did not mention anything other than these words in which he has expressed his right due to him from the people, for he is the grandson of the Apostle of Allah, may Allah bless him and his family, who was faithful to their religion and their world, and took them out of the life of error and estrangement, so if they had carried out his right and installed him as a caliph, then it would have been obligatory on him to establish in their regions justice in all its senses and concepts.

Al-'Abbas delivers a Speech
Al-'Abba`s, the orator, delivered an eloquent, wonderful speech and ended it with this poetry line:
There is no escape for the people from having a sun and a moon, so you are a sun, and this is that moon.

Persons abstain from pledging Allegiance to the Imam
Some persons abstained from pledging allegiance to the Ima`m, for they harbored malice against him, hated him, and were indignant with al-Ma'mu`n because of his appointing the Ima`m as a successor after him. They are as follows:
1. 'Isa al-Juludi.
2. 'Ali Bin 'Umra`n.
3. Abu` Yunus.
Al-Ma'mu`n ordered them to be arrested and imprisoned.

Al-Ma'mun orders them to be executed
He ordered these three persons to be taken out of the prison. When they stood before him and saw Ima`m al-Rida` sitting beside him, they became so angry that 'Ali b. 'Umra`n addressed al-Ma'mu`n, saying: "I seek refuge for you, O Commander of the faithful, with Allah from taking out this authority, which Allah has vested in you and with which He has singled you out, and placing it in the hands of your enemies and those whom your forefathers had killed and made homeless in the land."
"O Son of the adulteress," shouted al-Ma'mu`n at him, "why have you insisted on that?"
Then he ordered his head to be struck off. Then Abu` Yunus was brought before him. When he saw the Ima`m sitting beside al-Ma'mu`n and enjoying honor and magnification, he became displeased and addressed al-Ma'mu`n, saying: "O Commander of the faithful, by Allah, this (one) who is sitting beside you worships an idol apart from Allah."
As a result al-Ma'mu`n ordered him to be executed, and he was executed. Then 'Isa al-Julu`di was brought into his presence. It is worth mentioning that he was the mortal enemy of the members of the House (ahl al-Bayt), peace be on them. It was he whom Harun al-Rashïd had sent to Medina (Yathrib) in order to loot and confiscate the garments and jewels of the granddaughters of Allah's Messenger, may Allah bless him and his family.
Accordingly, he went to the house of Ima`m al-Rida`, peace be on him, intended to break into it and to loot the garments of the 'Alawide ladies.
The Ima`m refused that, but al-Julu`di paid no attention to him. So the Ima`m began entreating him and promising him that he would go in and bring him what he wanted. Al-Julu`di yield to the words of the Ima`m, who went in, gathered the garments and jewels of the 'Alawide ladies, and gave them to him. He took them and went away. As for the Ima`m, he asked al-Ma'mu`n to pardon al-Julu`di, but he refused him vigorously, saying: "O my master, it is this (person) who had looted (the garments and jewels) of the granddaughters of Mohammed, may Allah bless him and his family!"
Al-Juludi looked at the Ima`m when he was speaking to al-Ma'mu`n and entreating him in order to pardon him, but the stupid one (i.e. al-Julu`di) thought that the Ima`m intended to avenge himself upon him because of what he had done toward him, so he said to al-Ma'mu`n: "O Commander of the faithful, I ask you through Allah and my service to al-Rashï~d not to accept the statement of this (i.e. the Ima`m) concerning me." Al-Ma'mu`n turned to Ima`m al-Rida` and said to him: "O Abu` al-Hasan, he has asked me for pardon, and we regard his oath as true."
Then he addressed al-Julu`di, saying: "No, by Allah, I will not accept his statement concerning you." Then he turned to the police men and said to them: "Let him join his friend!" So he was advanced and his head was struck off.

Important Decrees
Al-Ma'mu`n issued some important decrees on the occasion of appointing Ima`m al-Rida`, peace be on him, as a successor. They are as follows:
1. Giving salaries to the soldiers for one full year.
2. Abandoning the black uniform of the 'Abba`sids , and dressing in green. I (i.e. the author) think that the inhabitants of the Garden will be dressed in green, for Allah, the Most High, says: "And they shall wear green robes of fine silk and thick silk. "
3. Striking dirhams and dinars with the name of Ima`m al-Rida`, peace be on him. Al-Sayyid 'Abd al-Qa`dir Ahmed al-Yusuf has mentioned some examples of that currency as follows:

(The Dinar)
It has been written in the center of its face: "There is no god but Allah, the One without associate with Him." It has been written in the girth: "In the name of Allah, this dinar was struck in Samarqand in the year 202." And it has been written in the circle: "Allah's is the command before and after, and on that day the believers shall rejoice at Allah's help."
It has been written in the center of the back: "Allah, Mohammed is Allah's Messenger, al-Ma'mu`n is the vicegerent of Allah, of what the Emir al-Rida`, the regent over the Muslims, 'Ali b. Mu`sa` b. 'Ali b. Abu` Ta`lib has commanded."
And it has been written in the circle of the center of the back: "Mohammed is the Messenger of Allah; He has sent him with guidance and the religion of truth, that He might cause it to prevail over all religions, though the polytheists may be averse."

(The Dirham)
'Abd al-Qa`dir has moved the shape of the dirham from Berlin Museum numbered 1295. The formula of the writing in the center of the face is: "There is no god but Allah, the One without an associate with Him." in the year 203.
The writing in the circle is: "Allah's is the command before and after, and on that day the believers shall rejoice at Allah's help." The writing in the back is: "Allah, Mohammed is Allah's Messenger, al-Ma'mu`n is the vicegerent of Allah, of what al-Rida` has commanded." The writing in the circle is: "Mohammed is the Messenger of Allah; He has sent him with guidance and the religion of truth, that He might cause it to prevail over all religions, though the polytheists may be averse."
Another shape of the dirham available in the British Museum in London, number 289 is as follows:
The writing in the center of the face is: "There is no god but Allah, the One without an associate with Him."
The writing in the girth is : "the year"
The writing in the circle is: "Allah's is the command before and after."
The writhing in the center of the back is: "It was commanded by the Emir of the Muslims, 'Ali b. Musa...'Ali b. Abu` Ta`lib...Dhu al-Riya`satayn." The writing in the circle is: "Mohammed is the Messenger of Allah."
These dots show that some letters have been erased, for they have copied in this manner in the world catalogs. This writing has been erased because the currency is very old and used very much. There are examples of the dirhams which were struck in the year 704 A. H., the same as the currency of the Ima`m, and it has been written in them what had been written in the original currency.

The Imam marries al-Ma'mun's Daughter
Al-Ma'mu`n asked Ima`m al-Rida`, peace be on him, to marry the Princess, Mrs. Umm Habïb ; the Ima`m accepted that and married her. Al-Ma'mu`n intended to seek nearness to the Ima`m, that the relationships between them might be strong. Some traditionalists think that al-Ma'mu`n married his daughter to the Ima`m in order to spy on his behavior and activities. This step suits al-Ma'mu`n, who is famous for deception and trickery.

The Pledge of Allegiance to the Imam in all Cities
Al-Ma'mu`n ordered all his governors over all Islamic cities and regions to take from all citizens the pledge of allegiance to Ima`m al-Rida` regarding regency. The following are some cities where the pledge of allegiance to him was taken:

1. Madinah (Yathrib)
All popular classes in Madinah (Yathrib) happily received the news of regency of Ima`m al-Rida`, peace be on him. The governor of Medina, 'Abd al-Jabba`r al-Masa`hiqi, hurried to the mosque of the Prophet in order to take from the inhabitants of the city the pledge of allegiance (to the Ima`m). That was after al-Ma'mu`n's command concerning that.
He ascended the pulpit and addressed the people, saying: "O People, this is the matter for which you have wished, the justice for which you have waited, and the good for which you have hoped. This is 'Ali b. Mu`sa` b. Ja'far b. Mohammed b. 'Ali b. al-Husayn b. 'Ali b. Abu` Ta`lib, the peace of Allah be upon them. "
The pledge of allegiance to Ima`m al-Rida` was the most important and valuable hope for which the Muslim community waited, for it impatiently waited for the return of the rule to the Ima`m, that he might establish pure justice among it, spread security and welfare among its regions, and save it from the oppression and tyranny of the 'Abba`sids.

2. Egypt
Al-Ma'mu`n wrote to his governor over Egypt, al-Sari, and ordered him to take from the Egyptians the pledge of allegiance to his successor Ima`m al-Rida`. The letter came to al-Sari in the month of Muhrrah, in the year 202. So al-Sari started taking the pledge of allegiance to the Ima`m, peace be on him. But Ibra`him b. al-Mahdi, the leader of the singers in Baghdad, spoiled this pledge of allegiance, for he wrote to the prominent soldiers and their commanders in Egypt and ordered them to depose al-Ma'mu`n and his heir apparent and to revolt against al-Sari.
So some of them responded to him, among them were al-Ha`rith b. Zar'a b. Mahzam at al-Fista`t, 'Abd al-'Aziz al-Wazir al-Jarawi at the bottom of the land, Sala`ma b. 'Abd al-Malik al-Azdi al-Taha`wi at al-Sa'ïd, Sulayma`n b. Gha`lib b. Gabriel, and 'Abd al-'Aziz b. 'Abd al-Rahma`n b. 'Abd al-Jabba`r al-Azdi. As a result they revolted against al-Sari, summoned the people to pledge allegiance to Ibra`him, and appointed 'Abd al-'Aziz al-Azdi as a governor over Egypt.
So al-Sari warred against them, captured 'Abd al-'Aziz and a group of his family. He killed some of them, sent some of them along with 'Abd al-'Aziz's daughter to al-Ma'mu`n, and he ordered them to be killed. The rest went to al-Harawri in order to protect them. In this manner the revolt was suppressed, and the people pledged allegiance to the Ima`m.

3. Mecca
Al-Ma'mun sent 'Isa al-Juludi to Mecca in order to take from its people the pledge of allegiance to the Ima`m, and in Mecca was Ibra`him, the brother of Ima`m al-Rida`, peace be on him. 'Isa al-Juludi summoned the Meccans to pledge allegiance to the Imam, peace be on him, and to dress in green. So they responded to him with happiness and thankfulness, invoking (Allah) for al-Ma'mu`n for accomplishing their wish and hope through this pledge of allegiance.

4. Kufa
The overwhelming majority in Ku`fa received the news of the pledge of allegiance to the Ima`m with happiness and delight. Al-Ma'mun entrusted al-'Abbas, the son of Ima`m Musa, peace be on him, with taking from the Kufans the pledge of allegiance (to the Imam). Ibrahim b. 'Abd al-Hamid gave him one hundred thousand dirhams and said to him: "Fight on behalf of your brother, for the Kufans respond to you for that, and I am along with you." Al-'Abba`s undertook this task, so a large group of them responded to him. A group of people said to him:
"If you summon (us) to al-Ma'mun and then after him to your brother, then we are in no need of your summons; and if you summon (us) to your brother or to some of the members of your household or to yourself, then we will respond to you." So al-'Abbas said to them: "I summon (you) to al-Ma'mu`n in the first place, and then after him to my brother, al-Rida."
These people abstained from pledging allegiance to the Imam, condemned those who pledged allegiance to him, and summoned them to break the pledge of allegiance. When Ibra`him b. al-Mahdi came to know about the desertion of the Kufans, he ordered his army residing at the Nile and under the leadership of Sa'ïd and Abu al-Bït to occupy Kufa and suppress the mutiny. The armies of Ibrahim marched and arrived at al-Qantara near Dïr al-A'war.
There they were hindered by a military force headed by the 'Alawide, 'Ali b. Mohammed b. Ja'far and Abu 'Abd Allah, the brother of the great leader Abu` al-Sara`ya`, so it met them, and finally the armies of Ibra`him b. al-Mahdi won a victory (over it). Then the armies of Ibra`him advanced towards Ku`fa; they were dressed in black; their motto was:
"O Mansu`r there is no obedience to al-Ma'mu`n." The Ku`fans cowered and were unable to war against them, so they sent a delegation to the commander-in-chief of the army of Ibra`him in order to give security to al-'Abba`s and his group, and he responded to them for that and made it a condition on them that al-'Abba`s and his companions should leave Ku`fa. Then the delegation came back to al-'Abba`s, who had no knowledge of that, and said to him: "Surely all your followers are mobs; you will see that the people will face war, loot, and murder; therefore, leave us; we are in no need of you."
Accordingly, al-'Abba`s left Ku`fa while he was sad and sorrowful. He came to know that the Ku`fans would not protect him; nor would they fulfill their promise and covenant toward him. Then the armies of Ibra`him entered Ku`fa, but no clashes took place between them and those who pledged allegiance to the Ima`m as a heir apparent. These are some of the regions where the pledge of allegiance to the Ima`m was taken as a heir apparent.