The iconoclast persecution
Prokopios lived during the first phase of the Byzantine iconoclast controversy, when the emperor Leo III the Isaurian (reigned 717-741) condemned the veneration of icons and a persecution arose against those who honored them. Against this policy Prokopios defended the Orthodox distinction between worship, which belongs to God alone, and the veneration shown to icons, which passes to the person represented.
According to the synaxarion, he was arrested at the emperor's command and subjected to harsh torments, being flogged, beaten with rods, and raked with iron claws before being cast into prison. He endured this confinement until the emperor's death, after which he and his companions were released.