Sunan an-Nasa'i 4404
سنن النسائي#4404SahihIt 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)
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Abu GhuddahSahih
Al-AlbaniSahih
Zubair Ali ZaiHasan
In-book reference: 43:44