سنن النسائي

It was narrated from Abu Malik Al-Ashja'i that his father said: "I prayed behind the Messenger of Allah (ﷺ) and he did not say the Qunut, and I prayed behind Abu Bakr and he did not say the Qunut, and I prayed behind Umar and he did not say the Qunut, and I prayed behind Uthman and he did not say the Qunut, and I prayed behind Ali and he did not say the Qunut." Then he said: "O my son, this is an innovation."