Yahya related to me from Malik from Abu'z Zinad from al-Araj from
Abu Hurayra that the Messenger of Allah, may Allah bless him and grant
him peace, said, "Do you see the direction I am facing here? By Allah,
neither your concentration nor your ruku is hidden from me. I can see
you behind my back."
Muwatta Malik Book 9, Hadith 78