Musannaf Ibn Abi Shayba 3:6075

Abu Mu’awiyah narrated to us, from Hajjaj, from al-Hakam, from Abd al-Rahman ibn Yazid, from Abdullah, who said: Two things are an innovation: that a man stands after he finishes his prayer, facing the Qibla, supplicating; and that he performs the second prostration, then thinks it is a duty upon him to press his buttocks to the ground before he rises.