Sahih Bukhari Volume 2, Book 21, Hadith Number 275.

Narated By Ibn ‘Umar : I remember ten Rakat of Nawafil from the Prophet, two Rakat before the Zuhr prayer and two after it; two Rakat after Maghrib prayer in his house, and two Rakat after ‘Isha’ prayer in his house, and two Rakat before the Fajr prayer and at that time nobody would enter the house of the Prophet Hafsa told me that the Prophet used to offer two Rakat after the call maker had made the Adhan and the day had dawned.