The Prophet ﷺ said, "Perform the bowing and prostration properly, for by Allah, I see you from behind me," and sometimes he said, "from behind my back, when you bow and prostrate."
عن النبي ﷺ قال: أقيموا الركوع والسجود، فوالله إني لأراكم من بعدي- وربما قال: من بعد ظهري إذا ركعتم وسجدتم.
Bukhari related it in the Book of Adhan (742), and Muslim in the Book of Prayer (425), both from Muhammad bin Bashshar, who said, Muhammad bin Jafar Ghundar narrated to us, who said, Shuba narrated to us, who said, I heard Qatada, from Anas, and he mentioned the hadith.