I am 90% certain that this is not an authentic desert father story (though I would be delighted to be convinced otherwise), but it’s a lovely, poignant story and worthy of being shared.
With the Sign of the Cross, the old monk Abba Joseph trapped in his cell a dark and miserable demon who had come to tempt him.
“Release me, Father, and let me go,” pleaded the demon, “I will not come to tempt you again”.
“I will gladly do that, but on one condition,” replied the monk. “You must sing for me the song that you sang before God’s Throne on high, before your fall.”
The demon responded, “You know I cannot do that; it will cause me cruel torture and suffering. And besides, Father, no human ear can hear its ineffable sweetness and live, for you will surely die.”
“Then you will have to remain here in my cell,” said the monk, “and bear with me the full struggle of repentance.”
“Let me go, do not force me to suffer,” pleaded the demon.
“Ah, but then you must sing to me the song you sang on high before your fall with Satan.”
So the dark and miserable demon, seeing that there was no way out, began to sing, haltingly, barely audible at first, groping for words long forgotten. As he sang, the darkness which penetrated and surrounded him began slowly to dissipate. The song grew ever louder and increasingly stronger, and soon the demon was caught up in its sweetness, his voice fully lifted up in worship and praise. Boldly he sang of the power and the honour and the glory of the Triune God on High, Creator of the Universe, Master of Heaven and Earth, of all things visible and invisible. As the song sung on high before all ages resounded in the fullness of its might, a wondrous and glorious light penetrated the venerable Abba’s humble cell, and the walls which had enclosed it were no more. Ineffable love and joy surged into the very depths of the being of the radiant and glorious angel, as he ever so gently stooped down and covered with his wings the lifeless body of the old hermit who had liberated him from the abyss of hell.