"I said to 'Aishah: 'Tell me of a supplication that the Messenger of Allah ﷺ used to say in his prayer.' She said: 'Yes. The Messenger of Allah ﷺ used to say: Allahumma inni author bika min sharri ma 'amiltu wa min sharri ma lam a'mal (O Allah, I seek refuge with You from the evil of that which I have done, and the evil of that which I have not done.)'" (Using translation from Nasāʾī 1307)  

قُلْتُ لِعَائِشَةَ حَدِّثِينِي بِشَيْءٍ كَانَ رَسُولُ اللهِ ﷺ يَدْعُو بِهِ فِي صَلَاتِهِ فَقَالَتْ نَعَمْ كَانَ يَقُولُ «اللهُمَّ إِنِّي أَعُوذُ بِكَ مِنْ شَرِّ مَا عَمِلْتُ وَمِنْ شَرِّ مَا لَمْ أَعْمَلْ»