Musnad Abu Ya'la al-Mawsili 152:339

'Abd al-Rahman ibn Salam narrated to us, Ibrahim ibn Tahman narrated to us, from Abu Ishaq, from Abu 'Ubaydah, from 'Abdullah ibn Mas'ud, that he said: When "When the victory of Allah has come and the conquest" (Surah An-Nasr) was revealed until the end of the surah, the Messenger of Allah (peace and blessings of Allah be upon him) would frequently say: "Glory be to You, our Lord, and with Your praise. O Allah, forgive me, for You are the Accepting of repentance."