Musannaf Ibn Abi Shayba 21:588

Ibn Fudayl narrated to us, from ‘Ata’ ibn al-Sa’ib, from Abu ‘Abd al-Rahman, who said: Ibn Mas‘ud taught us to say in the Qunut—meaning in the Witr: "O Allah, we seek Your help and we seek Your forgiveness, and we praise You 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 for 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."