Musannaf Ibn Abi Shayba 3:4659

Waki' narrated to us, he said: Sufyan narrated to us, from Mutarrif, from Abu al-Jahm, from al-Bara', that he performed Qunut in the Fajr prayer. He said "Allahu Akbar" when he finished the recitation, and he said "Allahu Akbar" when he bowed.