Musnad Ahmad 30:744

Muhammad ibn Bishr narrated to us, Muhammad ibn ‘Amr narrated to us, Abu Salamah narrated to us, from Abu Hurairah, who said: The Prophet, peace and blessings of Allah be upon him, passed by a man lying on his stomach. He said: "Indeed, this is a lying posture that Allah, the Almighty and Majestic, does not love."