سنن ابن ماجه

It was narrated that Rafi’ bin Khadij said: “We were with the Prophet (ﷺ) on a journey, and I said: ‘O Messenger of Allah, we are (sometimes) on military campaigns, and we have no knife with us.’ He said: ‘(Use) whatever causes the blood to flow, mention the Name of Allah and eat, but (do not use) teeth or nails, for the tooth is a bone and the nail is the knife of the Ethiopians.”