Sahih Muslim Book 4, Hadith 118
This hadith is transmitted by Muhammad b. Rafi', Abu'I-Razzaq. Ma'mar, Hammam on the authority of Abu Huraira with the addition of (the word)" prayer".
This hadith is narrated on the authority of Abu Huraira by another chain of transmitters.
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.