رَبَّنَا ظَلَمْنَا أَنْفُسَنَا وَإِنْ لَمْ تَغْفِرْ لَنَا وَتَرْحَمْنَا لَنَكُونَنَّ مِنَ الْخَاسِرِينَ
Rabbana zalamna anfusana wa in lam taghfir lana wa tarhamna lanakuanna minal-khasirin
Unser Herr, wir haben uns selbst Unrecht getan. Wenn Du uns nicht vergibst und Dich unser erbarmst, werden wir gewiss zu den Verlierern gehören.
Recite when seeking forgiveness for sins and mistakes
This was the first dua of repentance taught to humanity. Adam and Hawwa (Eve) said this after their sin, and Allah accepted their repentance.