Messenger of Allah ﷺ said, "Do you consider or see that my face is towards the Qibla? By Allah, neither your submissiveness nor your bowing is hidden from me, surely I see you from my back."  

أَنَّ رَسُولَ اللَّهِ ﷺ قَالَ هَلْ تَرَوْنَ قِبْلَتِي هَا هُنَا فَوَاللَّهِ مَا يَخْفَى عَلَىَّ خُشُوعُكُمْ وَلاَ رُكُوعُكُمْ إِنِّي لأَرَاكُمْ مِنْ وَرَاءِ ظَهْرِي  

The Prophet ﷺ led us in a prayer and then got up on the pulpit and said, "In your prayer and bowing, I certainly see you from my back as I see you (while looking at you.)"  

صَلَّى بِنَا النَّبِيُّ ﷺ صَلاَةً ثُمَّ رَقِيَ الْمِنْبَرَ فَقَالَ فِي الصَّلاَةِ وَفِي الرُّكُوعِ إِنِّي لأَرَاكُمْ مِنْ وَرَائِي كَمَا أَرَاكُمْ