In 838 Ishaq supervised the execution of 'Abdallah, the brother of the defeated Khurramite rebel Babak al-Khurrami, and gibbeted his corpse in Baghdad.[13] In 840 he took into custody Mazyar, the captured rebel prince of Tabaristan, after the latter had arrived in Iraq; upon receiving him, Ishaq ordered him to be transported on an elephant and escorted him to the caliph in Samarra. That same year he formed part of the tribunal that prosecuted the disgraced general al-Afshin, which ended with al-Afshin being found guilty of apostasy and thrown into prison.[14]