Musannaf Ibn Abi Shayba 3:1393

Waki' narrated to us, from Ibn 'Awn, from Raja' ibn Haywah, from Mahmud ibn Rabi', who said: I prayed a prayer, and by my side was 'Ubadah ibn al-Samit. He recited the Opening of the Book (al-Fatihah). I said to him, "O Abu al-Walid, did I not hear you recite the Opening of the Book?" He said, "Yes, for there is no prayer except with it."