Abu al-Malih reported: Uthman ibn Affan, may Allah be pleased with him, entered his house to find his servant boy playing in the trough of a camel. Uthman took him by the ear and twisted it, but he later regretted what he did. He said to him, “Take my ear and twist it.” Uthman made him do it, telling him to pull harder and harder, until he thought what had been done to himself was the same as he did. Uthman said, “How easy is retribution in the world before retribution in the Hereafter!”
Source: al-Ahwāl li-Ibn Abī Dunyā 255
عَنْ أَبِي الْمَلِيحِ الرُّقِّيِّ قَالَ دَخَلَ عُثْمَانُ بْنُ عَفَّانَ رضي الله عنه عَلَى غُلَامٍ لَهُ يَعْلِفُ نَاقَةً فَرَأَى فِي عَلَفِهَا فَأَخَذَ بِأُذُنِ غُلَامِهِ فَعَرَجَهَا ثُمَّ نَدِمَ فَقَالَ لَهُ خُذْ بِأُذُنِي فَاعْرُجْهَا فَجَعَلَ عُثْمَانُ يَقُولُ لَهُ شُدَّ شُدَّ حَتَّى ظَنَّ أَنَّهُ قَدْ بَلَغَ مِنْهُ مِثْلَ مَا بَلَغَ مِنْهُ قَالَ عُثْمَانُ وَاهًا لِقِصَاصِ الدُّنْيَا قَبْلَ قِصَاصِ الْآخِرَةِ
255 الأهوال لابن أبي الدنيا