`Aishah (May Allah be pleased with her) reported: The Prophet (PBUH) never omitted four Rak`ah prayer before the Zuhr prayer and two Rak`ah prayers before dawn (Fajr) prayer.[Al-Bukhari].
This Hadith tells us the practice of the Prophet (PBUH) in respect of the four Rak`ah Sunnah of Zuhr prayers and the two of Fajr prayers. He (PBUH) used to perform both regularly. Such Rak`ah are called Sunnah Rawatib or Sunnah Mu'akkadah (compulsory prayers).