Shortening the Prayer

Malik :: Book 9 : Hadith 9.23.73

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."