Sahih Muslim
The Book Pertaining to the Remembrance of Allah, Supplication, Repentance and Seeking Forgiveness (Kitab Al-Dhikr)
Book Number: 035 / Hadith Number: 6558
Farwa' b. Naufal reported: I asked 'A'isha about the supplication that Allah's Messenger (may peace be upon him) made. She said that he used to say:" O Allah, I seek refuge in Thee from the evil of what I have done and from the evil of what I have not done."