Imam Musa Kazim was summoned and imprisoned by the Abbasid caliphs several times during his Imamate. The first time was during the caliphate of Mahdi Abbasi, when the Imam was transferred from Medina to Baghdad by order of the caliph. Harun also imprisoned the Imam twice. The time of the first arrest and imprisonment is not mentioned in the sources, but the second time was on 20 Shawwal 179 AH in Medina and on 7 Dhul-Hijjah he was imprisoned in the house of Isa ibn Ja'far in Basra. According to Sheikh Mufid, Harun wrote a letter to Isa ibn Ja'far in 180 AH asking him to kill the Imam, but he refused.
After a while, the Imam was transferred to the prison of Fadl ibn Rabi' in Baghdad. Imam Kazim (AS) spent the last years of his life in the prisons of Fadl ibn Yahya and Sindi ibn Shahak.
In the Ziyarat of Imam Kazim (AS), he is greeted with the phrase الْمُعَذَّبِ فِي قَعْرِ السُّجُون; the one who was tortured in the dungeons. In the Ziyarat of the Imam, his prison is also mentioned as ظُلَمْمِرِ. A prison in which it is impossible to stretch one's legs and sleep is called a matmura. Also, the underground prisons of Baghdad were humid and damp (matmura) due to their proximity to the Tigris.
There are different reports in the sources about the reason why the seventh Shiite Imam was arrested by the Abbasid caliphs and transferred to prison. According to some reports, the reason for the arrest of Musa ibn Ja'far on the orders of Harun was the jealousy of Yahya Barmaki and the slander of Ali ibn Isma'il ibn Ja'far, his nephew, to Harun.
It is said that Harun was sensitive to the Shiites' relationship with Imam Kazim and feared that the Shiites' belief in the Imamate of the Imam would weaken his government.
Also, according to some reports, the reason for Imam Kazim's (a.s.) imprisonment was that some Shiites, such as Hisham ibn Hakam, did not comply with the Imam's wishes, even though the Imam had ordered them to practice taqiyyah. These reports have listed Hisham ibn Hakam's debates as one of the reasons for the Imam's imprisonment.
