The Book Pertaining to the Remembrance of Allah, Supplication, Repentance and Seeking Forgiveness (Kitab Al-Dhikr)
Muslim :: Book 35 : Hadith 6557
Farwa' b. Naufal Ashja'i reported: I asked: 'A'isha, in what words did Allah's Messenger (may peace be upon him) supplicate Allah? She said that he used to utter:" I seek refuge in Thee from the evil of what I did and from the evil of what I did not."