Sayyidina Rafi ibn Khadij (RA) narrated: I said, 0 Messenger of Allah! We will meet our enemy tomorrow and we do not have a knife with us (to slaughter an animal). He said, That which sheds blood and the name of Allah is called over it, eat that, except if it is tooth or claw. I shall tell you about that. As for teeth, it is bone. And as for claw, it is the knife of Abyssinia.
[Bukhari 5498, Muslim 1968]