Musnad Ahmad 5:86

Muhammad ibn Ubayd narrated to us, Sharhabil ibn Mudrik al-Ju'fi narrated to us, from Abdullah ibn Naji al-Hadrami, from his father, who said: Ali said to me: "I had a status with the Messenger of Allah, peace and blessings of Allah be upon him, that no one among the creation had. I used to come to him every pre-dawn and greet him until he would clear his throat. One night I came and greeted him, and I said: 'Peace be upon you, O Prophet of Allah.' He said: 'Stay where you are, O Abu al-Hasan, until I come out to you.' When he came out to me, I said: 'O Prophet of Allah, did someone anger you?' He said: 'No.' I said: 'Then why did you not speak to me as you used to do in the past, until you spoke to me tonight?' He said: 'I heard a movement in the room, so I said: Who is this? He said: I am Gabriel. I said: Enter. He said: No, come out to me. When I went out, he said: There is something in your house that an angel will not enter as long as it is in it. I said: I do not know what it is, O Gabriel. He said: Go and look. So I opened the house and found nothing in it except a puppy that al-Hasan was playing with. I said: I found nothing but a puppy. He said: There are three things that an angel will never enter as long as one of them is present: a dog, or a state of major ritual impurity (janabah), or an image of a living being.'"