It is mentioned in Faslul Khitab that at the time of sunrise he used to go into a prostration for the Creator and he used to so much prolong this prostration that it extended upto noontime. Due to intensive worship he had become so lean and emaciated that people barely recognized him. It seemed as if only a white cloth was lying on the prayer mat. Seeing the level of his worship, once Harun Rashid said: You are the monk and the pious one of Bani Hashim.
During the period he was in prison, it was customary for him to complete his morning prayer, recite the additional supplications and devotions and then go into a prostration and remain thus till noon. After the decline of the sun from its zenith he used to raise his head and perform the Noon (Zuhr) Prayer. Then he spent the whole day in worship. At night he slept for a few moments and spent the rest of the night in worship. After the Noon (Zuhr) and Afternoon (Asr) prayers he used to go into prostration and remain in this position till sunset. As soon as it was evening he stood up for the evening (Maghrib) prayer. After the evening prayer he recited the supplications till the time of the Night (Isha) prayers. Again after the Night (Isha) prayers he began to recite supplications and invocations. When he finished all this he broke his fast and used to eat a little food then go into prostration of thanks. Then after sleeping for a little while he was engrossed in the Midnight prayer till it was the time for Morning Prayer.
One day Harun Rashid sent a very attractive slave girl to the prison to seduce the Imam in any way possible. She came to the prison and employed all the tactics but to no avail. The Imam was not even slightly attracted by her. On the other hand the intensive worship of the Imam and his devotional recitations in the court of Allah had such profound effect on the maid that she began to regret her own evil intentions and became engrossed in Allah’s worship. When Harun was informed of this he summoned her and asked, “Why did you not perform the job I sent you for?” She said, “O Chief! Listen! This man is not human. He is an angel. How could I have attracted him? I had gone to attract him towards myself but on the contrary his spirituality affected me.” After that, the slave girl receded into seclusion and spent the rest of her life in worship.
Reference :Akhlaq al-A’imma, Morals & Manners of the Holy Imams