Феодор Студит
Upon the death of Leo V, the iconoclast persecution dissipated, permitting internal struggles within the church to rise to the forefront. One of these involved accusations by several bishops and abbots that Peter exorcised demons not by the power of God, but rather the power of Beelzebub. Peter tried to convince them otherwise, unsuccessfully, and ultimately had to seek the help of Theodore the Studite in persuading them. Theodore wrote a letter to all the monks of the area, telling them that Peter was in fact above reproach in conduct, teachings, and beliefs, and was as good a monk as could be found. This letter survives to this day.