Imam Malik's Muwatta, Chapter: Shortening the Prayer

Yahya related to me from Malik from Yahya ibn Said from an-Numan ibn Murra that the Messenger of Allah, may Allah bless him and grant him peace, said,"What about drunkenness, stealing and adultery? "That was before anything had been revealed about them. They said, "Allah and His Messenger know best." He said, "They are excesses and in them is a punishment. And the worst of thieves is the one who steals his prayer." They said, "How does he steal his prayer, Messenger of Allah?" He replied, "He does not do ruku or sajda properly."