Musannaf Ibn Abi Shayba 33:1403

Al-Fadl ibn Dukayn narrated to us, he said: Al-A’mash narrated to us, from Yazid ibn Hayyan, who said: ‘Anbas ibn ‘Uqbah al-Taymi—of Taym al-Rabab—used to prostrate until the sparrows would land upon his back and descend, not considering him to be anything but the stump of a wall.