Musnad Ahmad 1034:19

Abu Mu'awiyah narrated to us, Al-A'mash narrated to us, from Zayd ibn Wahb, who said: Hudhayfah entered the mosque, and there was a man praying near the doors of Kindah, and he was not completing the bowing (ruku') nor the prostration (sujud). When he finished, Hudhayfah said to him: "How long has this been your prayer?" He said: "For forty years." Hudhayfah said to him: "You have not prayed for forty years, and if you were to die while this is your prayer, you would die upon a nature other than the nature upon which Muhammad, may Allah bless him and grant him peace, was created." Then he turned to him to teach him, and said: "Indeed, a man may be quick in his prayer, yet he still completes the bowing and the prostration."