Musannaf Ibn Abi Shayba 3:1243

Yazid ibn Harun narrated to us, he said: Muhammad ibn Ishaq informed us, from Yahya ibn 'Abbad ibn 'Abdullah ibn al-Zubayr, from his father, from 'Aishah, from the Prophet (peace and blessings of Allah be upon him), who said: "Every prayer in which the Opening of the Book (Fatihat al-Kitab) is not recited is deficient (khidaj)."