وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ أَبِي الزِّنَادِ، عَنِ الأَعْرَجِ، عَنْ أَبِي هُرَيْرَةَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ ‏"‏ أَتَرَوْنَ قِبْلَتِي هَاهُنَا فَوَاللَّهِ مَا يَخْفَى عَلَىَّ خُشُوعُكُمْ وَلاَ رُكُوعُكُمْ إِنِّي لأَرَاكُمْ مِنْ وَرَاءِ ظَهْرِي ‏"‏ ‏.‏

Yahya related to me from Malik from Abu'z Zinad from al-Araj fromAbu Hurayra that the Messenger of Allah, may Allah bless him and granthim peace, said, "Do you see the direction I am facing here? By Allah,neither your concentration nor your ruku is hidden from me. I can seeyou behind my back." Translation Not Available

Book Ref: Muwatta Imam Malik Book 9 Hadith 404
Web Ref:  Muwatta Imam Malik Book 9 Hadith 73