Musannaf Ibn Abi Shayba 3:1376

3753. 'Abd al-A'la narrated to us, from Ma'mar, from al-Zuhri, from 'Ubayd Allah ibn Abi Rafi', that 'Ali used to say: "Recite in the Dhuhr and the 'Asr behind the Imam, in every rak'ah, the Mother of the Book (al-Fatiha) and a surah."