The Messenger of Allah (ﷺ) said the Qunut for one month, supplicating against one of the 'Arab tribes, then he stopped doing that."
Sunan an-Nasa'i Book 12, Hadith 51
← Previous Hadith He heard the Prophet (ﷺ), when he raised his head in the last rak'ah of the subh prayer, say: "O Allah, curse so-and-so and so-and-so," supplicating against some of the hypocrites. Then Allah revealed the words: "Not for you is the decision; whether He turns in mercy to (pardon) them or punishes them; verily, they are the wrongdoers."

Sunan an-Nasa'i Book 12, Hadith 50 Next Hadith → "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."

Sunan an-Nasa'i Book 12, Hadith 52