God’s messenger ordered us to kill dogs, and we were even killing a dog which a woman brought with her from the desert. Afterwards God’s messenger forbade us to kill dogs, saying, "Confine yourselves to the type which is pure black and has two spots, for it is a devil."
Abu Huraira reported God’s messenger as saying, "If anyone gets a dog, except a sheepdog or a hunting dog or a farm dog, a qirat of his reward will be deducted daily."
Ibn ‘Umar reported God’s messenger as saying, "If anyone acquires a dog, except a sheepdog or one trained for hunting, two qirats will be deducted from his good deeds daily."