Musnad Abu Ya'la al-Mawsili 150:262

Khalaf ibn Hisham al-Bazzar narrated to us, Abu 'Awanah narrated to us, from Qatadah, from Zurarah, from Sa'd ibn Hisham, from 'Aishah, that the Prophet (peace and blessings of Allah be upon him) said: "The two rak'ahs of the dawn (prayer) are better than the world and what is in it."