Sunan an-Nasa'i, Volume 5, Book 45, Hadith 4773 (DarusSalam) ⓘ

It was narrated that Ya'la bin Umayyah said: "I went on a campaign with the Messenger of Allah in the Army of Hardship, and this was the deed of which I was most sure. I had a hired man who fought with another person. One of them bit the finger of the other, who pulled his finger away and a front tooth fell out. He went to the Prophet who considered the tooth to be in vain, and said: "Would he put his hand in your mouth for you to bite it?"

أَخْبَرَنَا يَعْقُوبُ بْنُ إِبْرَاهِيمَ، قَالَ حَدَّثَنَا ابْنُ عُلَيَّةَ، قَالَ أَنْبَأَنَا ابْنُ جُرَيْجٍ، قَالَ أَخْبَرَنِي عَطَاءٌ، عَنْ صَفْوَانَ بْنِ يَعْلَى، عَنْ يَعْلَى بْنِ أُمَيَّةَ، قَالَ غَزَوْتُ مَعَ رَسُولِ اللَّهِ صلى الله عليه وسلم جَيْشَ الْعُسْرَةِ - وَكَانَ أَوْثَقَ عَمَلٍ لِي فِي نَفْسِي - وَكَانَ لِي أَجِيرٌ فَقَاتَلَ إِنْسَانًا فَعَضَّ أَحَدُهُمَا أُصْبَعَ صَاحِبِهِ فَانْتَزَعَ إِصْبَعَهُ فَأَنْدَرَ ثَنِيَّتَهُ فَسَقَطَتْ فَانْطَلَقَ إِلَى النَّبِيِّ صلى الله عليه وسلم فَأَهْدَرَ ثَنِيَّتَهُ وَقَالَ ‏ "‏ أَفَيَدَعُ يَدَهُ فِي فِيكَ تَقْضَمُهَا ‏" ‏ ‏.‏