John was first the chief minister to Caliph Abdul-Malik and later a monk in the Monastery of St. Sava the Sanctified. Because of his ardent defense of the veneration of icons during the reign of the iconoclastic Emperor Leo the Isaurian, John was maligned by the emperor to the Caliph, who cut off his right hand. John fell down in prayer before the icon of the Most-holy Theotokos, and his hand was rejoined and miraculously healed. Seeing this miracle the Caliph repented, but John no longer desired to remain with him as a nobleman. Instead, he withdrew to a monastery, where, from the beginning, he was a model to the monks in humility, obedience and all the prescribed rules of monastic asceticism. John composed the Funeral Hymns and compiled the Octoechos (The Book of Eight Tones), the Irmologion, the Menologion and the Paschal Canon, and he wrote many theological works of inspiration and profundity. A great monk, hymnographer, theologian and soldier for the truth of Christ, St. John is numbered among the great Fathers of the Church. He entered peacefully into rest in about the year 776 at the age of 104.
Source: St. Nikolai Velimirovic, The Prologue of Ohrid – Volume Two.
You are a guide of Orthodoxy, a teacher of piety and modesty, a luminary of the world, the God inspired pride of monastics. O wise John, you have enlightened everyone by your teachings. You are the harp of the Spirit. Intercede to Christ our God for the salvation of our souls.