Abu Huraira reported
One day the Messenger of Allah (ﷺ) led the prayer. Then turning (towards his Companions) he said: O you man, why don't you say your prayer well? Does the observer of prayer not see how he is performing the prayer, for he performs it for himself? By Allah, I see behind me as I see in front of me.
Abu Huraira reported
The Messenger of Allah (ﷺ) 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.
Anas b. Malik reported. The Messenger of Allah (ﷺ) said
Perform bowing and prostration well. By Allah, I see you even if you are behind me, or he said: (I see you) behind my back when you bow or prostrate.
Anas reported
The Apostle of Allah (ﷺ) said: Complete the bowing and prostration well. By Allah, I see you behind my back as to how you bow and prostrate or when you bow and prostrate.