Musannaf Ibn Abi Shayba 3:1374

Ibn ‘Ulayyah narrated to us, from Layth, from ‘Abd al-Rahman ibn Tharwan, from Hudhayl, from ‘Abdullah ibn Mas‘ud, that he recited in the ‘Asr [prayer] behind the Imam, in the two rak‘ahs, the Opening of the Book (al-Fatihah) and a surah.