Sahih Muslim , Book 4, Hadith 854 (USC-MSA) ⓘ
Abu Huraira reported: The Messenger of Allah said: Do you find me seeing towards the Qibla only? By Allah, your bowing and your prostrating are not hidden from my view. Verily I see them behind my back.
حَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، عَنْ مَالِكِ بْنِ أَنَسٍ، عَنْ أَبِي الزِّنَادِ، عَنِ الأَعْرَجِ، عَنْ أَبِي هُرَيْرَةَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " هَلْ تَرَوْنَ قِبْلَتِي هَا هُنَا فَوَاللَّهِ مَا يَخْفَى عَلَىَّ رُكُوعُكُمْ وَلاَ سُجُودُكُمْ إِنِّي لأَرَاكُمْ وَرَاءَ ظَهْرِي " .
also referenced under: Book 4, Hadith 120 (In-Book) & Hadith 424 (Reference)