Sayyiduna Ibn Abbas (may Allah be pleased with them both) narrates that the Prophet Muhammad (peace be upon him) for a whole month, after every prayer—Dhuhr, Asr, Maghrib, Isha, and Fajr—in the last rak'ah, when he would say «‏‏‏‏سَمِعَ اللهُ لِمَنْ حَمِدَهُ» ‏‏‏‏, he would make Qunoot. The Prophet (peace be upon him) would supplicate against the tribes of Banu Sulaym: Ri'l, Dhakwan, and 'Usayyah, and the companions praying behind him would say Ameen. He states that the Prophet (peace be upon him) had sent (some reciters of the Qur'an) to them to invite them to Islam, but they killed them. 'Ikrimah says that this hadith is the key to the (legitimacy of) the supplication of Qunoot.