Sahih Bukhari Volume 3, Book 37, Hadith 2266

حَدَّثَنِى يَعْقُوبُ بْنُ إِبْرَاهِيمَ، حَدَّثَنَا إِسْمَاعِيلُ ابْنُ عُلَيَّةَ، أَخْبَرَنَا ابْنُ جُرَيْجٍ، قَالَ أَخْبَرَنِي عَطَاءٌ، عَنْ صَفْوَانَ بْنِ يَعْلَى، عَنْ يَعْلَى بْنِ أُمَيَّةَ ـ رضى الله عنه ـ قَالَ غَزَوْتُ مَعَ النَّبِيِّ صلى الله عليه وسلم جَيْشَ الْعُسْرَةِ فَكَانَ مِنْ أَوْثَقِ أَعْمَالِي فِي نَفْسِي، فَكَانَ لِي أَجِيرٌ، فَقَاتَلَ إِنْسَانًا، فَعَضَّ أَحَدُهُمَا إِصْبَعَ صَاحِبِهِ، فَانْتَزَعَ إِصْبَعَهُ، فَأَنْدَرَ ثَنِيَّتَهُ فَسَقَطَتْ، فَانْطَلَقَ إِلَى النَّبِيِّ صلى الله عليه وسلم فَأَهْدَرَ ثَنِيَّتَهُ وَقَالَ ‏"‏ أَفَيَدَعُ إِصْبَعَهُ فِي فِيكَ تَقْضَمُهَا ـ قَالَ أَحْسِبُهُ قَالَ ـ كَمَا يَقْضَمُ الْفَحْلُ ‏"

Narrated By Ya'la bin Umaya : I fought in Jaish-al-Usra (Ghazwa of Tabuk) along with the Prophet and in my opinion that was the best of my deeds. Then I had an employee, who quarrel led with someone and one of the them bit and cut the other's finger and caused his own tooth to fall out. He then went to the Prophet (with a complaint) but the Prophet cancelled the suit and said to the complainant, "Did you expect him to let his finger in your mouth so that you might snap and cut it (as does a stallion camel)?"