Sayyiduna Abdullah bin Abbas (may Allah be pleased with him) says that the Messenger of Allah (peace and blessings be upon him) performed Qunoot continuously for one month in the prayers of Dhuhr, Asr, Maghrib, Isha, and Fajr. When he would say "Sami' Allahu liman hamidah" in the last rak'ah, he would perform this Qunoot, in which he would supplicate against the tribes of Banu Sulaym: Ri'l, Dhakwan, and 'Usayyah, and the followers behind him would say Ameen. The reason for this was that the Prophet (peace and blessings be upon him) had sent some companions to these people to invite them to Islam, but they killed them. In his narration, Affan said that Ikrimah used to say that this was the reason for the beginning of this Qunoot.