Abba ammonas and the woman in the barrel
A group of monks approached Abba Ammonas, calling upon him to punish a local hermit and fellow monk who they heard had a mistress living with him. Infuriated at their neighbor's casual immorality, the monks asked Ammonas to accompany them to the monk's cell, where they would confront the culprit.
When the hermit heard that his brothers were planning to punish him for his sins, he hid his mistress in a large barrel. The crowd of monks appeared with Ammonas in the lead. As soon as he entered the monk's cell, Ammonas realized that the woman was hiding in the cask. Strolling over to it, he sat down on the barrel and then instructed the other monks to search the cell carefully.
When the monks had searched everywhere without finding the woman, they retreated, abashed and apologetic. On his way out, Ammonas took his fellow monk's hand and offered the classic monastic axiom. "Brother, be on your guard; pay attention to yourself."