From the Wisdom of the Desert Fathers.

In a monastery there were two remarkable brothers who soon merited to see the grace of God descend upon each other. Now one day it happened that one of them went out of the monastery on a Friday and saw someone who was eating in the morning, and he said to him, ‘Why are you eating at this hour on a Friday?’ Later there was the synaxis [assembly] as usual. Now his brother saw that grace had withdrawn from him, and he was grieved. When they had returned to the cell he said to him, ‘My brother, what have you done? Indeed, I do not see the grace of God upon you as it used to be.’ The other answered him, ‘I am not aware of having done anything wrong, either in act or in thought.’ His brother said to him, ‘Have you spoken any words?’ Then he remembered and said, ‘Yesterday I saw someone who was eating outside the monastery early in the day, and I said to him, ‘Why are you eating at this hour on a Friday?’ This is my sin. But labor with me for two weeks, praying God to forgive me.’ They did this, and at the end of two weeks one brother saw the grace of God come upon the other and they were comforted and gave thanks to God.