What feature did the Prophet Muhammad (saw) say separates a black dog from a red dog and a yellow dog?
 Abu Dharr reported:                      The Messenger of 'Allah (may peace be upon him) said: When any one of you stands for prayer and there is a thing before him equal to the back of the saddle that covers him and in case there is not before him (a thing) equal to the back of the saddle, his prayer would be cut off by (passing of an) ass, woman, and black Dog. I said: O Abu Dharr, what feature is there in a black dog which distinguish it from the red dog and the yellow dog? He said: O, son of my brother, I asked the Messenger of Allah (may peace be upon him) as you are asking me, and he said: The black dog is a devil.