Sa'id bin al-Musayyab and Abu Salamah bin Abd al-Rahman (may Allah have mercy on them both) narrate that Sayyiduna Abu Hurayrah (may Allah be pleased with him) said: When the Messenger of Allah (peace and blessings be upon him) finished the recitation in the Fajr prayer, he would say the takbir and go into ruku'; then, when he raised his head from ruku', he would say: 'Sami'a Allahu liman hamidah, Rabbana wa laka al-hamd' (Allah hears the one who praises Him; our Lord, and to You belongs all praise). Then, while still standing, he would say: 'Allahumma anji al-Walida bna al-Walid, wa Salamata bna Hisham, wa Ayyasha bna Abi Rabi'ah, wal-mustad'afina mina al-mu'minin. Allahumma-shdud wat'ataka ala Mudar, waj'alha alayhim sinina ka-sini Yusuf. Allahumma-l'an Lihyana wa Ri'lan wa Dhakwana wa Usayyata asat Allaha wa rasulah' (O Allah, rescue al-Walid bin al-Walid, Salamah bin Hisham, Ayyash bin Abi Rabi'ah and the weak and helpless Muslims. O Allah, seize the disbelievers of the tribe of Mudar with Your severe grip, and lengthen the period of this punishment upon them like the famine of Yusuf. O Allah, send Your curse upon Lihyan, Ri'l and Dhakwan, and curse Usayyah too, who disobeyed Allah and His Messenger). Then, when this verse was revealed, the Messenger of Allah (peace and blessings be upon him) abandoned the qunut, namely: "You have no say at all in the matter; (Allah may) either accept their repentance or punish them, for they are wrongdoers" [Surah Al Imran: 128].
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 3085