Musnad Ahmad 32:567

Ishaq ibn Isa narrated to us, he said: Malik informed me, from al-Ala, who said: We entered upon Anas ibn Malik after the noon prayer, and he stood to pray the afternoon prayer. When he finished his prayer, we discussed the hastening of the prayer. He said: I heard the Messenger of Allah, peace and blessings of Allah be upon him, say: "That is the prayer of the hypocrites," three times. "One of them sits until, when the sun turns yellow and is between the two horns of a devil, he stands and pecks four [rak'ahs], not remembering Allah in them except a little."