(88) CHAPTER. Submissiveness in As-Salat (the prayer).
Narrated Abu Huraira: Allah's Apostle said, You see me facing the Qibla; but, by Allah, nothing is hidden from me regarding your bowing and submissiveness and I see you from behind my back.
Narrated Anas bin Malik: The Prophet said, Perform the bowing and the prostrations properly. By Allah, I see you from behind me (or from behind my back) when you bow or prostrate.