question #2 Sahih Muslim 423, Book 4, Hadith 119 : How does the ability of the Prophet (ﷺ) to see behind him emphasize the importance of sincerity in prayer?

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.