They say that Abba Macarius the Egyptian [St. Macarius the Great] on one occasion went up from Scete to the Nitrian mountain, and as he drew near to a certain place, he said to his disciple, "Pass on a little in front of me"; and when he had done so there met him a certain heathen priest, who was running along and carrying some wood about the time of noon. And that brother cried out to him and said, "O minister to devils, where run thou?"  And the priest turned round and smote him with many severe blows, and he left him with but very little breath remaining in him, and he took up his wood and went on his way; and when he had gone on a little further the blessed Macarius met him on his journey, and said to him, "May you be helped, O man of labours?"  And the priest was astonished, and came to him and said, "What fair thing have you seen in me that you should salute me [in this gracious fashion] ?"  And the old man said to him, "I see that you toil, and that you do not know that you are toiling for naught"; then he said to the old man, "At your salutation I also was very sorry, and I learned that you did belong to the Great God. But a wicked monk met me just before you didst, and he cursed me, and I smote him even to death."  And the old man knew that it was his disciple [of whom he spake], and the priest laid hold upon the feet of Macarius, and said to him, "I will not let you [go] until you make me a monk"; and they came to the place where the brother was lying, and they carried him and brought him to the church of the mountain. Now when the fathers saw the heathen priest with him, they marvelled that he had been converted from the error which he had held; and Macarius took him and made him a monk, and through him many of the heathen became Christians. And Abba Macarius said, " ' An evil word makes wicked even those who are good, and a good word makes good even those who are wicked,' as it is written."

from Sayings of the Holy Desert Fathers

Three old men once came to Abba Sisoes [St. Sisoes the Great] because they had heard that he was a great man. And the first one said unto him, "Father, how can I escape from the river of fire?" And Abba Sisoes answered him never a word. Then the second old man said to him, "Father, how can I escape from the gnashing of teeth, and from the worm which never dies?" And Abba Sisoes answered him never a word. Then the third old man said to him, "Father, what will I do? For the remembrance of the outer darkness troubles me." And Abba Sisoes answered and said to them, "I never think on any of these things, but I believe that God is Merciful, and that He will show mercy to me"; then the old men went away grieved at the answer which Abba Sisoes had spoken to them. Now because he did not wish to send them away sorrowful, he brought them back, and said to them, "Blessed are ye, O my brothers, for I have been jealous of you"; and they said to him, "In what matter have you been jealous of us?" And he said, "The first one of you spake about a river of fire; and the second spake about the gnashing of teeth and the worm which dies not; and the third spake about the outer darkness; if remembrances of this kind have dominion over your minds it is impossible for you to commit sin. What can I do who am stubborn of heart? For hardness of heart will not allow me to perceive even that there a punishment for men existeth, and because of this I sin every hour." And when the old men had heard these words, they made excuses to him, and said, "In very truth according to what we have heard, even so have we seen."

from Sayings of the Holy Desert Fathers

He who will not accept a reproof, just or unjust, renounces his own salvation. But he who accepts it with an effort, or even without an effort, will soon receive the remission of his sins.

St. John Climacus