Like his forefather, Amir'ul-Mu'minin (a.s), Imam Reza (a.s) also used to pray a thousand rakats (units) of prayers in a day and night. He concluded his prayers before a little while before noon and till the time of sunset at the end of the day. Otherwise most of the time he used to stand on his prayer mat. He also remained very thoughtful and contemplative. After completing the Morning Prayer he used to be engrossed in recitations and supplications and he prolonged the glorifications of God to such an extent that it was mid-morning. At this time he went into prostration of thanks to remain therein till noon. After that he issued admonitions and advices and returned to his prayer mat for the noon prayer. He recited the supererogatory (nawafil) till the sun began to decline from its zenith. After the noon prayer he prolonged his recitations and then performed the prostration of thanks. He used to recite: Thanks be to Allah (Shukran Lillaah) a hundred times. Thus, this type of worship continued till midnight. Then he slept for sometime and arose for the midnight prayer.
Mamun tried his utmost to involve the Imam in the affairs of the government but how could he do that? One day Mamun said, "O son of the Messenger of Allah! I fear that you may perish due to excess worship." Imam (a.s) replied, "Such a death is everlasting success." Mamun said, "What sins have you committed that you pray day and night for their forgiveness?" Imam (a.s) replied, "Not for the forgiveness of sins, it is for the thankfulness of His bounties. It is the demand of my servitude."

Valour Of Imam Reza (a.s)
Numerous incidents connected with the bravery and courage of Imam Reza (a.s) are recorded in the books of history. Here we can only mention one or two of such anecdotes.
Mamun invited Imam Reza (a.s) to his state capital and insisted upon him to accept his heir apparency. The Imam (a.s) continued to refuse it and told him in unequivocal terms that he would never be able to become his heir. He said that he would be poisoned to death before Mamun died. Mamun said, "Who can dare kill you, as long as I live?" The Imam said, "If it had not be expedient I would have even told you the name of my killer." When Mamun realized that he was not relenting he was infuriated and he said, "By this refusal you aim to become famous for your piety and abstemiousness and that my helpless and weakness may become obvious." Imam said, "I have never lied in my life. It does not befit me to pretend austerity for the sake of material gains. But your insistence in this matter shows that you want to prove to the world that Ali Ibne Musa (a.s) was not abstemious in the real sense. Material wealth had itself deserted him for some time. And when it came back to him he became involved in it with all desire and fondness."
Hearing this reply Mamun became more angry and making a show of his apparent strength and power said, "If you do not accept my heir-apparency and continue to refuse it, I would have you killed." Imam (a.s) said, "If the matter has reached to this point, I will accept it with the conditions that I will not be involved in administration, I would not refrain from enjoining good and forbidding evil and I will never support you in an unlawful matter."
It is mentioned in Uyoon Akhbar ar-Reza that when Mamun held the commemorative function to celebrate the appointment of Imam Reza (a.s) as the heir apparent, he requested the Holy Imam (a.s) to deliver a sermon. The Imam came to the pulpit and after invoking praise on the Almighty and glorifications of the Holy Prophet (S) he said,
"People! Due to our relationship with the Messenger of Allah! We have a right upon you and in the same way you have a right upon us. When you have fulfilled our rights it is also necessary on us to observe your rights. Thanks be to Allah that He has protected those of our rights that people had destroyed and raise those of our affairs that people had demolished. For a period of eighty years the people of disbelief and disobedience used to invoke curse upon us from the pulpits and they continued to hide our excellences and made false allegations against us. But Allah intended that out fame should rise high.
O People! I did not accept the heir-apparency because I desire post and status and I am desirous of rulership. I accepted it so that if I see you walking on the wrong path I may restrain you, whether you listen to me or not. I inform you that I will never hesitate in the expression of truth, even though I may be killed for this. The existence of us, Ahl ul-Bayt in the world is only for the purpose that we may fearlessly support truth."

Piety Of Imam Reza (a.s)
During hot season he sat on a sack and during cold, he sat on a blanket. At home he wore a dress of coarse and thick cloth. This was very uncomfortable to the body. However, when he went out, he used to wear fine clothes, so that people may not ridicule him to be a miser. One day a Sufi of Medina saw him wearing fine clothes and objected to it. The Imam caught his hand put it inside his sleeve to show him that he was wearing coarse woolen clothes inside and the outward dress was only for the people so that they may not label him an outwardly pious man, and the dress of coarse wool was to keep the body in penance.
When Mamun appointed the Imam as his heir apparent, he reserved a section of his royal palace for the Imam. The Imam expressed to him his dislike in residing in it. He said that such mansions were for kings and not for Ahl ul-Bayt. So Mamun asked what type of a dwelling the Imam preferred. Imam said, "A very ordinary place having no inconvenience. It shouldn't have any means of comfort, there should not be a sentry at the door and there should not be any hindrance to the visitors. The floor should be covered with a mat." Mamun said, "You are my heir-apparent, such a house is not suitable for you." But the Imam said, "I like only such a kind of place." At last Mamun relented and said, "You may choose any house for yourself." Imam (a.s) selected a dilapidated house near the royal palace and began to reside in it.

Patience Of Imam Reza (a.s)
During the period Imam Reza (a.s) resided in Merv as the heir apparent of the caliph there was an Abbaside leader who was very jealous of him. He was always waiting for an opportunity to degrade the Imam in the eyes of Mamun, but he did not get any chance. One day he came to the Imam and criticizing the Shiite religion began to foul-mouth the Imam. The Imam asked him, "O Man! After all, what is your aim with this?" "To insult you!" he replied. The Imam said, "The special servants of Allah are never humiliated." "I do not consider you among the chosen servants of Allah," he said. The Imam said, "When did I ask you to consider me thus? But the One Whose servant I am considers me thus." He said, "Show me a miracle and I will accept it." The Imam said, "Is it anything less than a miracle that you are talking in such a bad way and I am maintaining patience and self-control? Can I not complain to the ruler and have you punished severely?" Hearing this the man became regretful and fell down at the feet of the Imam and said, "From today I have become your devotee. I had come with the intention to make you behave arrogantly with me so that I can fight you and defame you in the town. But I have become a devotee of your good behavior. The fact is that being on such an important position the patience and forbearance you have shown is impossible by anyone else."

Humility Of Imam Reza (a.s)
Someone remarked to the Imam, "By Allah! No one is superior to you as regards lineage and ancestry." He replied, "All the virtues my ancestors possessed were due to their piety and obedience of Allah and not due to something else." The man said, "By Allah! You are better than ordinary people." The Imam replied with perfect humility, "O man, do not swear by Allah regarding this. One who has better piety than me is superior to me. By Allah! This verse has not been abrogated:

Forgiveness Of Imam Reza (a.s)
When Mamun decided to appoint Imam Reza (a.s) his heir apparent, the Abbasides opposed this very much and uttered many unbecoming words regarding the Imam (a.s). One of them went to the extent of calling the Imam an ignorant fellow (God forbid
in the Imam's presence. When Mamun learnt about it he wanted to punish this courtier. But the Imam restrained him and said, "Forgive him like I have forgiven." This fellow was surprised at the forgiveness of the Imam. The Imam said, "We Ahl ul-Bayt overlook the mistakes of those who are unaware of our status."

Affection Of Imam Reza (a.s)
During the time Imam Reza (a.s) was the heir-apparent of Mamun, it was his practice to roam the town on foot every day in search of people in need and then try to solve their difficulties. When Mamun learnt about it, he told the Imam one day, "I have heard that you go out sight-seeing on foot while conveyance is available for you. Why do you take this trouble?" The Imam replied, "I do not go for sight-seeing, I go to study the condition of poor Muslims." Mamun said, "You can go for this also on a horse back." Imam (a.s) said, "In that case the downtrodden people would not meet me freely. Seeing my affluent manner they would be repelled and would not dare to approach me." Mamun was shocked on getting this reply and after some time he said, "It is a fact that affection towards creatures is truly the job of you Ahl ul-Bayt only."

Hospitality Of Imam Reza (a.s)
A major portion of the pension that the Imam received during the period of his heir-apparency of Mamun was spent in entertaining guests. People visited him from far-flung areas. One day Mamun came to meet him. He saw that the house of Imam (a.s) was teeming with guests and the Imam was busy in serving them. Mamun inquired who these people were. "They are all my guests", replied the Imam. Mamun said, "Being on the honorable post of heir-apparent it does not befit you that like a commoner you serve these ordinary people. So many servants are there at you service, let them take care of these people." The Imam said, "Being your heir-apparent, it may not befit me, but being the grandson of the Messenger, it is my duty that I serve my guests. We Ahl ul-Bayt are very fond of guests."

Imam Reza’s (a.s) Kindness To Relatives
During the time Imam Reza (a.s) resided in Medina some of his relatives were antagonistic to him, especially due to the fact that the spirituality of the Imam was effective on all and people used to respect him greatly. However, the Imam behaved with all of them in a very kind and affectionate way and also sent them occasional gifts. The Imam's family members tried to restrain him from this. He said, "This is the only difference between Ahl ul-Bayt and others, that we always repay bad behavior with goodness and we are kind to the relatives."

Imam Reza’s (a.s) Kind Behavior To Slaves
Abu Bakr Suli says that his grandmother used to narrate: I and three friends of mine were in the service of Imam Reza (a.s) for many years. The Imam took very less work from us. One day we said to him, "Mamun has sent us to serve you and not to live in comfort." The Imam said, "It is my service only that you fulfill the obligations of Allah." The Holy Imam used to teach us the religious rules everyday. Being in the Imam's service I memorized nearly 400 traditions, that now I have forgotten. Most of the time it so happened that the Imam used to fill up a pot of water for ritual ablution (wuzu), kept it besides us and then awoke us in a very very gentle way saying, "This is not the time to sleep, it is time for Allah's remembrance." We used to be very ashamed of such affection of the Holy Imam. When he was martyred we were sent back to Mamun's house. But in spite of all the facilities available there I felt very lonely and the royal palaces seemed like dark dungeons. I used to remember the Imam (a.s) and weep day and night.

Imam Reza’s (a.s) Kind Behavior To Slaves
Abu Bakr Suli says that his grandmother used to narrate: I and three friends of mine were in the service of Imam Reza (a.s) for many years. The Imam took very less work from us. One day we said to him, "Mamun has sent us to serve you and not to live in comfort." The Imam said, "It is my service only that you fulfill the obligations of Allah." The Holy Imam used to teach us the religious rules everyday. Being in the Imam's service I memorized nearly 400 traditions, that now I have forgotten. Most of the time it so happened that the Imam used to fill up a pot of water for ritual ablution (wuzu), kept it besides us and then awoke us in a very very gentle way saying, "This is not the time to sleep, it is time for Allah's remembrance." We used to be very ashamed of such affection of the Holy Imam. When he was martyred we were sent back to Mamun's house. But in spite of all the facilities available there I felt very lonely and the royal palaces seemed like dark dungeons. I used to remember the Imam (a.s) and weep day and night.