Abu Dawud Book 2, Hadith Number 1438.

Chapter : On reciting the supplication in prayer.

Narated By Abdullah ibn Abbas : The Apostle of Allah (PBUH) recited the supplication (Qunut) daily for a month at the noon, afternoon, sunset, night and morning prayers. When he said: “Allah listens to him who praises Him” in the last rak’ah, invoking a curse on some clans of Banu Sulaym, Ri’l, Dhakwan and Usayyah, and those who were standing behind him said: Amen.