Dua of forgiveness (Surah Ali Imran)

وَالَّذِينَ إِذَا فَعَلُوا فٰحِشَةً أَوْ ظَلَمُوٓا أَنفُسَهُمْ ذَكَرُوا اللَّهَ فَاسْتَغْفَرُوا لِذُنُوبِهِمْ وَمَن يَغْفِرُ الذُّنُوبَ إِلَّا اللَّهُ وَلَمْ يُصِرُّوا عَلٰى مَا فَعَلُوا وَهُمْ يَعْلَمُونَ

Transliteration

Wallazeena izaa fa'aloo faahishatan aw zalamooo anfusahum zakarullaaha fastaghfaroo lizunoobihim wa man yaghfiruz-zunooba illallaahu wa lam yusirroo 'alaa maa fa'aloo wa hum ya'lamoon.

Meaning

And those who, when they commit an immorality or wrong themselves [by transgression], remember Allah and seek forgiveness for their sins - and who can forgive sins except Allah? - and [who] do not persist in what they have done while they know.

Source: Surah Ali Imran 3:135