Musnad Abu Ya'la al-Mawsili 128:12

Abu Khaythama narrated to us, Jarir narrated to us, from Muhammad ibn Ishaq, from al-Ala’ ibn Abd al-Rahman, who said: I entered upon Anas ibn Malik when we had prayed the Dhuhr [prayer]. His slave girl said to him, "The prayer." I said, "Which prayer, O Abu Hamza?" He said, "The Asr." I said, "We have only just prayed the Dhuhr now." He said, "I heard the Messenger of Allah, peace and blessings of Allah be upon him, saying: 'That is the prayer of the hypocrite; he leaves the prayer until, when it is at the horn of the devil or between the two horns of the devil, he stands and prays it, not remembering Allah except a little.'"