Musannaf Ibn Abi Shayba 21:597

Waki' narrated to us, from Sufyan, from Habib ibn Abi Thabit, from Abd al-Rahman ibn Suwayd al-Kahili, that Ali used to recite the Qunut in the dawn prayer with these two surahs: "O Allah, we seek Your help and we seek Your forgiveness, and we praise You with goodness and we do not disbelieve in You, and we cast off and abandon whoever acts wickedly against You. O Allah, You alone we worship, and to You we pray and prostrate, and to You we strive and hasten, and we hope for Your mercy and fear Your punishment; for Your punishment will surely overtake the disbelievers."