Imam Reza (as) was the best worshipper of his time. Even his enemies acknowledged this fact and could not ignore this prominent trait of his. Mamoon Rashid, the Abbasid caliph, for instance praises the virtues of Imam Reza (as) in the “Covenant of Allegiance”, in which he declared His Holiness as his successor.

Reja bin Zahhak, who forced Imam Reza (as) into exile from Medina to Marw (Khorasan) on the orders of Mamoon Rashid, the Abbasid caliph, also describes the Holy Imam’s piety and worship saying “I accompanied him from Medina to Marw.” I swear by Allah! I have never seen a man who remembered Allah all the time like him, nor have I seen a man more fearing Allah, the Mighty and High, than he. At day break he would say his morning-prayers. Finishing his prayer, he would stay in his place glorifying Allah, and reciting these phrases repeatedly ‘Praise is to Allah’, ‘Allah is Great’, ‘There is no god but Allah’, “O Lord, Bless Muhammad (saw) and his progeny” till sunrise. Then he would go down in prostration till sunrise. Then he would go down in prostration till forenoon. Then he would see the people, asking about their concerns and enjoining them to do good. This would last till noon.

Ibrahim bin Abbas, one of the high-ranking officials during Mamoon Rashid’s reign, said about the Holy Imam Reza’s worship.

Imam Reza (as) slept little at night, staying awake most of it. Most of the time, he stayed awake till the morning. He also often fasted. He used to fast three days of every month. He called this fasting “Fasting of Lifetime”. He was very charitable, giving out alms in secret to the needy, often at night. Who ever claims that he has seen someone else who matches him in his virtues, do not believe him.