Sayyid al-Istighfar (the best way of seeking forgiveness)
Sahihاللَّهُمَّ أَنْتَ رَبِّي، لاَ إِلَهَ إِلاَّ أَنْتَ، خَلَقْتَنِي وَأَنَا عَبْدُكَ، وَأَنَا عَلَى عَهْدِكَ وَوَعْدِكَ مَا اسْتَطَعْتُ، أَعُوذُ بِكَ مِنْ شَرِّ مَا صَنَعْتُ، أَبُوءُ لَكَ بِنِعْمَتِكَ عَلَىَّ وَأَبُوءُ لَكَ بِذَنْبِي، فَاغْفِرْ لِي، فَإِنَّهُ لاَ يَغْفِرُ الذُّنُوبَ إِلاَّ أَنْتَ
Allāhumma anta rabbī, lā ilāha illā anta, khalaqtanī wa ana 'abduk, wa ana 'alā 'ahdika wa wa'dika mastaṭa't, a'ūdhu bika min sharri mā ṣana't, abū'u laka bi-ni'matika 'alayya wa abū'u laka bi-dhanbī, faghfir lī, fa-innahu lā yaghfiru adh-dhunūba illā ant.
O Allah, You are my Lord; there is no god but You. You created me and I am Your servant, and I hold to Your covenant and promise as much as I can. I seek refuge in You from the evil of what I have done. I acknowledge Your favour upon me and I acknowledge my sin, so forgive me, for none forgives sins but You.
Virtue: Whoever says it during the day with certainty and dies that day before evening, or says it at night with certainty and dies before morning, is among the people of Paradise.