V.viii.9. Abba Cassian told how a certain brother came to abba Serapion, who asked him to say the prayers according to custom, but he wouldn’t, saying that he was a sinner and unworthy to be called a monk. When abba Serapion offered to wash his feet he likewise demurred using the same words. But the old man gave him something to eat and began to admonish him quite kindly, saying, “My son, if you wish to progress, go and stay in your cell, and look to yourself and your manual work. It will be more profitable for you to stay put rather than go out.” Abba Serapion could see from the young man’s face that he was very displeased at these words, so he went on to say, “You’ve just been saying that you were a sinner and almost unfit to live, so should you really get so upset because I give you some charitable advice? If you would be really humble learn to carry out cheerfully the tasks laid upon you by others without squandering yourself in shabby verbiage.” At this the brother begged the old man’s pardon and departed greatly edified.
From De Vitis Patrum, Book V.