Sayyid al-Istighfar (master of asking forgiveness)
اللَّهُمَّ أَنْتَ رَبِّي لَا إِلَهَ إِلَّا أَنْتَ، خَلَقْتَنِي وَأَنَا عَبْدُكَ، وَأَنَا عَلَى عَهْدِكَ وَوَعْدِكَ مَا اسْتَطَعْتُ، أَعُوذُ بِكَ مِنْ شَرِّ مَا صَنَعْتُ، أَبُوءُ لَكَ بِنِعْمَتِكَ عَلَيَّ، وَأَبُوءُ بِذَنْبِي فَاغْفِرْ لِي، فَإِنَّهُ لَا يَغْفِرُ الذُّنُوبَ إِلَّا أَنْتَ
Allahumma anta Rabbi, la ilaha illa anta, khalaqtani wa ana ‘abduk…
O Allah, You are my Lord, none has the right to be worshipped except You. You created me and I am Your slave, and I keep Your covenant and pledge as best I can. I seek refuge in You from the evil I have done. I acknowledge before You all the favours You have bestowed on me, and I acknowledge my sins, so forgive me — for none can forgive sins but You.
Source: Bukhari