Sahih Bukhari Volume 007, Book 067, Hadith Number 413.
Narrated By Mu'adh bin Sad or Sad bin Mu'adh : A slave girl belonging to Ka'b used to graze some sheep at Sl'a (mountain). Once one of her sheep was dying. She reached it (before it died) and slaughtered it with a stone. The Prophet was asked, and he said, "Eat it."