From the sayings of the Holy Fathers:
On one occasion Abba Ammon went to Abba Anthony, and he lost the way, and sat down for a little and fell asleep; and he rose up from his slumber, and prayed unto God, and said, “I beseech Thee, O Lord God, not to destroy that which “Thou hast fashioned.” Then he lifted up his eyes, and behold, there was the form of a man’s hand above him in the heavens, and it showed him the way until he came and stood above the cave of Abba Anthony.
Abba Anthony prophesiazed unto him, saying, “Thou shall increase in the fear of God.” Then he took him outside the cave, and showing him a stone, said, “curse this stone, and smite it” and he did so, and Abba Anthony said unto him, “It is thus that thou shall arrive at this state, for thou shall bear heaviness, and great abuse”; and this actually happened to Abba Ammon.
A young monk, going down from the skete to the city, passed by the but of Abba Ammoun and confessed to him: “My elder, Abba, is sending me to the city on an errand. I, however, who am a man of weakness, fear temptation.”
“Be obedient,” the holy man advised him, “and if temptation should arise before you, say these words: ‘O God of powers, through the intercession of my spiritual Father, deliver me.’”
The brother took courage from the words of the Abba and went immediately about his duty. The devil, however, who had been biding his time to bring harm to the monk, sent a woman of evil ways hastily to entrap him in her evil den. In his despair, the monk suddenly remembered the advice of Abba Ammoun and shouted with faith: “O God of powers, through the intercession of my spiritual Father, deliver me.”
He then found himself, without knowing how, on the road that led to the desert.
source: christian classics ethereal library