Sayyiduna Abu Rafi' (may Allah be pleased with him) said: The Messenger of Allah (peace and blessings be upon him) sent me to kill the dogs. So I went out and kept killing every dog I came across until I reached al-Asiyyah. There was a dog near a house, and I took aim at it to kill it. A woman called out to me from the house and said: What do you want? I said: The Messenger of Allah (peace and blessings be upon him) has sent me to kill the dogs. She said: Go back to the Messenger of Allah (peace and blessings be upon him) and tell him that I am a woman whose sight has gone, and this dog alerts me to whoever is coming and drives the wild beasts away from me. I went back to the Messenger of Allah (peace and blessings be upon him) and told him, and he (peace and blessings be upon him) said: "Go back and kill it." So I went back and killed it.
Hadith Referenceالمعجم الكبير للطبراني / باب الألف / 923