Sunan an-Nasai Book 43, Hadith 4404

أَخْبَرَنَا هَنَّادُ بْنُ السَّرِيِّ، عَنْ أَبِي الأَحْوَصِ، عَنْ سَعِيدِ بْنِ مَسْرُوقٍ، عَنْ عَبَايَةَ بْنِ رِفَاعَةَ، عَنْ أَبِيهِ، عَنْ جَدِّهِ، رَافِعِ بْنِ خَدِيجٍ قَالَ قُلْتُ يَا رَسُولَ اللَّهِ إِنَّا نَلْقَى الْعَدُوَّ غَدًا وَلَيْسَ مَعَنَا مُدًى ‏.‏ فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏ "‏ مَا أَنْهَرَ الدَّمَ وَذُكِرَ اسْمُ اللَّهِ عَزَّ وَجَلَّ فَكُلُوا مَا لَمْ يَكُنْ سِنًّا أَوْ ظُفْرًا وَسَأُحَدِّثُكُمْ عَنْ ذَلِكَ أَمَّا السِّنُّ فَعَظْمٌ وَأَمَّا الظُّفْرُ فَمُدَى الْحَبَشَةِ ‏"‏ ‏.‏

It was narrated that Rafi bin Khadij said:"I said: 'O Messenger of Allah we are going to meet the enemy tomorrow and we do not have any knives.' The Messenger of Allah said: "If the blood is shed and the name of Allah is mentioned, then eat, unless (it is slaughtered (with teeth or nails, and I will tell you about that. As for teeth, they are bones, and as for nails, they are the knives of the Ethiopians."' (Sahih)