Abu Malik al-Ashja'i narrates from his father, who said: "I prayed behind the Messenger of Allah (peace and blessings be upon him), Abu Bakr, Umar and Uthman (may Allah be pleased with them), and behind Ali (may Allah be pleased with him) here in Kufah for about five years, and they did not perform qunut in Fajr." Then he said: "My son, it is a newly introduced matter."
Hadith Referenceالمعجم الكبير للطبراني / باب الطاء / 8147