Musannaf Ibn Abi Shayba 3:1247

Abu Mu'awiyah narrated to us, from al-A'mash, from Khaythama, from 'Abayah ibn Rib'i, who said: 'Umar said: "A prayer in which the Opening of the Book (al-Fatiha) and two verses or more are not recited is not sufficient."