أَخْبَرَنَا عَمْرُو بْنُ مَنْصُورٍ، قَالَ حَدَّثَنَا حَفْصُ بْنُ عُمَرَ، - وَهُوَ الْحَوْضِيُّ - قَالَ حَدَّثَنَا جَامِعُ بْنُ مَطَرٍ، عَنْ عَلْقَمَةَ بْنِ وَائِلٍ، عَنْ أَبِيهِ، قَالَ كُنْتُ قَاعِدًا عِنْدَ رَسُولِ اللَّهِ صلى الله عليه وسلم جَاءَ رَجُلٌ فِي عُنُقِهِ نِسْعَةٌ فَقَالَ يَا رَسُولَ اللَّهِ إِنَّ هَذَا وَأَخِي كَانَا فِي جُبٍّ يَحْفِرَانِهَا فَرَفَعَ الْمِنْقَارَ فَضَرَبَ بِهِ رَأْسَ صَاحِبِهِ فَقَتَلَهُ ‏.‏ فَقَالَ النَّبِيُّ صلى الله عليه وسلم ‏"‏ اعْفُ عَنْهُ ‏"‏ ‏.‏ فَأَبَى وَقَالَ يَا نَبِيَّ اللَّهِ إِنَّ هَذَا وَأَخِي كَانَا فِي جُبٍّ يَحْفِرَانِهَا فَرَفَعَ الْمِنْقَارَ فَضَرَبَ بِهِ رَأْسَ صَاحِبِهِ فَقَتَلَهُ ‏.‏ فَقَالَ ‏"‏ اعْفُ عَنْهُ ‏"‏ ‏.‏ فَأَبَى ثُمَّ قَامَ فَقَالَ يَا رَسُولَ اللَّهِ إِنَّ هَذَا وَأَخِي كَانَا فِي جُبٍّ يَحْفِرَانِهَا فَرَفَعَ الْمِنْقَارَ - أُرَاهُ قَالَ - فَضَرَبَ رَأْسَ صَاحِبِهِ فَقَتَلَهُ ‏.‏ فَقَالَ ‏"‏ اعْفُ عَنْهُ ‏"‏ ‏.‏ فَأَبَى قَالَ ‏"‏ اذْهَبْ إِنْ قَتَلْتَهُ كُنْتَ مِثْلَهُ ‏"‏ ‏.‏ فَخَرَجَ بِهِ حَتَّى جَاوَزَ فَنَادَيْنَاهُ أَمَا تَسْمَعُ مَا يَقُولُ رَسُولُ اللَّهِ صلى الله عليه وسلم فَرَجَعَ فَقَالَ إِنْ قَتَلْتُهُ كُنْتُ مِثْلَهُ قَالَ ‏"‏ نَعَمِ اعْفُ ‏"‏ ‏.‏ فَخَرَجَ يَجُرُّ نِسْعَتَهُ حَتَّى خَفِيَ عَلَيْنَا ‏.‏

It was narrated from 'Alqamah bin Wa'il that his father said: "I was sitting with the Messenger of Allah when a man came with a string around his neck and said: 'O Messenger of Allah, this man and my brother were digging a hole, and he raised his pickax and struck his companion in the head, Killing him. 'The Prophet said: 'Forgive him,' but he refused and said: 'O Prophet of Allah, this man and my brother were digging a whole, and he raised his pickax and struck his companion in the head, killing him.' The Prophet said: 'Forgive him,' but he refused, then he stood up and said: 'O Messenger of Allah, this man and my brother were digging a hole, and he raised his pickax and struck his companion in the head, killing him.' The Prophet said: 'Forgive him,' but he refused. He (the prophet) said: 'Go, but if you kill him, you will be like him. So he took him out, and they called out to him: Didn't you hear what the Messenger of Allah said?' So he came back and he said: 'If I kill him will I be like him?' He said: 'Yes. Forgive him.' Then he went out, dragging his string, until he disappeared from our view." Translation Not Available

Book reference: Sunan An Nisai Book 45 Hadith 4726
Web reference: Sunan An Nisai Volume 5 Book 45 Hadith 4730