Musannaf Ibn Abi Shayba 35:248

Abu Khalid narrated to us, from Ibn 'Ajlan, from 'Ali ibn Yahya ibn Khallad, from his father, from his uncle—and he was a Badr-participant—who said: We were sitting with the Prophet, may Allah bless him and grant him peace, when a man entered and prayed. He performed a light prayer, not completing its bowing nor its prostration, while the Messenger of Allah, may Allah bless him and grant him peace, was watching him, and he (the man) did not perceive it. He prayed, then came and greeted the Prophet, may Allah bless him and grant him peace. The Prophet, may Allah bless him and grant him peace, returned the greeting to him and said, "Repeat, for you have not prayed." He did that three times, and each time he said, "Repeat, for you have not prayed."