Sayyiduna Qutbah bin Malik (may Allah be pleased with him) said: I prayed Fajr with the Prophet (peace and blessings be upon him), and in the first rak'ah he (peace and blessings be upon him) recited (Surah) "Qaf. By the glorious Qur'an" [Surah Qaf: 1].
Hadith Referenceالمعجم الكبير للطبراني / باب القاف / 16078