Sahih Bukhari Volume 003, Book 034, Hadith Number 270.
Narated By 'Adi bin Hatim : I asked Allah's Apostle about Al Mirad (i.e. a sharp-edged piece of wood or a piece of wood provided with a piece of iron used for hunting). He replied, "If the game is hit by its sharp edge, eat it, and if it is hit by its broad side, do not eat it, for it has been beaten to death." I asked, "O Allah's Apostle! I release my dog by the name of Allah and find with it at the game, another dog on which I have not mentioned the name of Allah, and I do not know which one of them caught the game." Allah's Apostle said (to him), 'Don't eat it as you have mentioned the name of Allah on your dog and not on the other dog."