Here you will find the Poem Ch 01 Manner of Kings Story 21 of poet Sa di
It is narrated that an oppressor of the people, a soldier, hit the head of a pious man with a stone and that the dervish, having no means of taking vengeance, preserved the stone till the time arrived when the king became angry with that soldier, and imprisoned him in a well. Then the dervish made his appearance and dropped the stone upon his head. He asked: "Who art thou, and why hast thou hit my head with this stone?" The man replied: "I am the same person whom thou hast struck on the head with this stone on such and such a day." The soldier continued: "Where hast thou been all this time?" The dervish replied: "I was afraid of thy dignity but now when I beheld thee in the well I made use of the opportunity."? When thou seest an unworthy man in good luck Intelligent men have chosen submission. If thou hast not a tearing sharp nail It will be better not to contend with the wicked. Who grasps with his fist one who has an arm of steel Injures only his own powerless wrist. Wait till inconstant fortune ties his hand. Then, to please thy friends, pick out his brains.