I asked Ayesha, Umm Muiminin, about the supplication the Messenger of Allah ﷺ used to make. She said that he used to say, "O Allah, I seek refuge in You from the evil of what I have done and from the evil of what I have not done."
حدثنا عثمان بن أبي شيبة حدثنا جرير عن منصور عن هلال بن يساف
سألت عائشة أم المؤمنين عما كان رسول الله ﷺ يدعو به قالت كان يقول اللهم إني أعوذ بك من شر ما عملت ومن شر ما لم أعمل
Muslim narrated it in "Remembrance and Supplication," in the chapter on supplications, no. 2716, from the hadith of Jareer bin Abdul-Hameed through this route.