It was narrated that 'Aishah said: "Jibril (A.S) promised the Messenger of Allah P.B.U.H that he would corne to him at a certain hour, but he was late. The Prophet P.B.U.H went out and there was Jibril standing at the door. He said: 'What kept you from entering?' He said: 'There is a dog in the house, and we do not enter a house in which there is a dog or an image:" (Sahih)