Musannaf Ibn Abi Shayba 3:3962

Ibn ‘Ulayyah and Ghundar narrated to us, from Shu’bah, from Ibrahim ibn Muhajir, from Ibrahim, who said: Ibn Mas’ud used to recite in the two rak’ahs before the morning prayer—or he said: before the dawn prayer—"Say, 'O disbelievers'" and "Say, 'He is Allah, [who is] One.'" Ghundar added: And in the two rak’ahs after the Maghrib prayer.