Musannaf Ibn Abi Shayba 3:3963

Ibn ‘Ulayyah narrated to us, from al-Jurayri, from Abu al-Sulayl, from Ghunaym ibn Qays, who said: We used to be commanded to challenge the Shaytan in the two rak'ahs before the morning [prayer] or before the dawn, with "Say, 'O disbelievers'" and "Say, 'He is Allah, [who is] One.'"