"A'isha reported that Gabriel (peace be upon him) made a promise with Allah's Messenger (may peace be upon him) to come at a definite hour; that hour came but he did not visit him. And there was in his hand (in the hand of Allah's Apostle) a staff. He threw it from his hand and said: Never has Allah or His messengers (angels) ever broken their promise. Then he cast a glance (and by chance) found a puppy under his cot and said: 'A'isha, when did this dog enter here? She said: By Allah, I don't know. He then commanded and it was turned out. Then Gabriel came and Allah's Messenger (may peace be upon him) said to him: You promised me and I waited for you. but you did not come, whereupon he said: It was the dog in your house which prevented me (to come), for we (angels) do not enter a house in which there is a dog or a picture."

(Sahih Muslim, Book 024, Number 5246:)

It is through this account that Muslims are forbidden to have dogs as pets. Muhammad ordered that dogs should be killed with the exception of those used specifically for protecting large property:

"Then on that very morning he commanded the killing of the dogs until he announced that the dog kept for the orchards should also be killed, but he spared the dog meant for the protection of extensive fields (or big gardens)."

Also; Sahih Muslim, Book 024, Number 5248:

It is also taught that Muslims who own dogs will lose "points" from their "good-deed rewards" that they are accumulating in order to gain "paradise:"