Sayyidul Istighfar
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
Allaahuma anta rabbee laailaaha illa ant, khalaqtanee wa ana 'abduk, wa ana 'ala 'ahdika wa w'adika masta-ta'tu, a'uthubika min sharri ma sana'tu, abu-u laka bi ni'matika 'alayya, wa abu-u bi-dhambi, faghfirlee finnahu laa yaghfiru-dhunooba illa ant
O Allah! You are my Lord; none has the right to be worshipped but You. You created me and I am Your slave and I am faithful to my covenant, and my commitment to You as far as I am able. I seek Your refuge from the evil of what I have done. I acknowledge before You all of the favours that You have bestowed upon me and I confess to you all my sins. Forgive me, for there is none who can forgive sins except You.
This Du'a is also referred to as 'Sayyidul Istighfaar' (The Master Du'a of seeking repentance). Whoever recites it during the day with firm conviction in it, and dies on the same day before the evening, he will be from the people of Paradise; and whoever recites it at night with firm conviction in it, and dies before the morning, he will be from the people of Paradise.