The Miḥnah (Arabic: محنة, English: "trial" or "testing") refers to the period of religious persecution instituted by the 'Abbasid Caliph al-Ma'mun in 833 AD in which religious scholars were punished, imprisoned, or even killed unless they conceded the Mu'tazila doctrine of the created nature of the Qur'an. The policy lasted for fifteen years (833–848 CE) as it continued through the reigns of al-Ma'mun's immediate successors, al-Mu'tasim and al-Wathiq, and two years of al-Mutawakkil who reversed it in 848 (or possibly 851) AD.
The abolition of Mihna is significant both as the end of the Abbasid Caliph's pretension to decide matters of religious orthodoxy, and as one of the few instances of specifically religious persecution in Medieval Islam.
In 827 CE, the caliph al-Ma’mun issued the proclamation of the doctrine of the createdness of the Qur'an. The proclamation was followed by the institution of the Mihna six years later, approximately four months before his sudden death in 833 CE. The Mihna continued under his successors, al-Mu’tasim and al-Wathiq, before al-Mutawakkil abolished it between 848 and 851 CE. This particular doctrine was well known to be embraced by the Mu'tazilite school during this period.
Traditional scholarship viewed the proclamation of doctrine and the Mihna where al-Ma’mun tested the beliefs of his subordinates as linked events, whereby the caliph exercised his religious authority in defining orthodoxy, and enforced his views upon others through his coercive powers as ruler. Al-Ma’mun’s motivations for imposing his beliefs upon the members of his government (such as his judges, for the scope of the Mihna was not extended to examining the beliefs of the commoners in the manner of the European Inquisitions) were attributed to his Mu'tazilite intellectual tendencies, his sympathies towards Shi’ism, or a shrewd decision to consolidate his religious authority during a time where the 'ulama were starting to be seen as the true guardians of religious knowledge and the Prophet’s traditions.