Sahih Bukhari
Hunting, Slaughtering
Volume: 007 / Book Number: 067 / Hadith Number: 441
Narrated Abu Huraira:
Allah's Apostle said, "None is wounded in Allah's Cause but will come on the Day of Resurrection with his wound bleeding. The thing that will come out of his wound will be the color of blood, but its smell will be the smell of musk."