Musnad Ahmad 32:1438

Yunus and Surayj narrated to us, they said: Fulayh narrated to us, from Hilal ibn Ali, from Anas. Yunus said: He said: The Messenger of Allah (ﷺ) performed a prayer. And Surayj said: The Messenger of Allah (ﷺ) performed a prayer for us one day, then he ascended the pulpit. He spoke about the prayer and about the bowing, then he said: "Indeed, I see you from behind me just as I see you from in front of me."