Muhammad bin 'Abdullah محمد بن عبد الله بن بزيع · The Book of ad-Dahaya (Sacrifices)

"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 )