Musannaf Ibn Abi Shayba 3:589

Abu Mu'awiyah narrated to us, from al-A'mash, from Zayd ibn Wahb, from Hudhayfah, that he entered the mosque. He found a man praying in a corner near the gates of Kindah, and he was not completing the bowing (ruku') and the prostration (sujud). When he finished, Hudhayfah said to him, "How long have you been praying like this?" He said, "For forty years." Hudhayfah said, "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 was created." Then he turned to him to teach him, and said, "Indeed, a man may lighten the prayer while [still] completing the bowing and the prostration."