Musannaf Ibn Abi Shayba 3:458

Abu Bakr narrated to us, he said: Ibn Numayr narrated to us, from al-A‘mash, from Muslim, from Masruq, who said: ‘Abdullah entered upon his brother and saw him praying upon a piece of wood, so he snatched it away and threw it. He said: "Make a gesture (for prostration) as far as your head reaches."