Musannaf Ibn Abi Shayba 3:4634

Abu Bakr narrated to us, he said: I heard Waki’ say: I heard Sufyan say: Whoever performs Qunut, then it is good, and whoever does not perform Qunut, then it is good. And if one performs Qunut, then the Qunut is only upon the Imam, and there is no Qunut upon those who are behind him.