Sayyiduna Rafi' bin Khadij (may Allah be pleased with him) says: I said: O Messenger of Allah, we are going to meet the enemy tomorrow and we have no knives. The Messenger of Allah (peace and blessings be upon him) said: "Whatever makes the blood flow and over which the name of Allah is mentioned, eat it, as long as it is not a tooth or a nail. I will tell you the reason for that: the tooth is bone, and the nail is the knife of the Abyssinians."
Hadith Referenceالمعجم الكبير للطبراني / باب الراء / 4370