Ascetic Struggle
The hagiographic tradition dwells at length on Peter's spiritual warfare in the cave near Korisha. The synaxarion relates that he was beset by demonic assaults taking the form of serpents, black ravens, and distracting visions intended to break his resolve.
By tradition, after forty days of fasting and fervent prayer the Archangel Michael appeared, overcame the tormenting serpent, and encouraged him to continue; thereafter Peter is said to have been granted a vision of the Uncreated, or divine, Light and consoled in his solitude. He reportedly healed those who came to him, and his renown gave rise to a regional veneration sometimes described as the 'Cult of Petar of Koriša.'