رَبَّنَا ظَلَمْنَا أَنْفُسَنَا وَإِنْ لَمْ تَغْفِرْ لَنَا وَتَرْحَمْنَا لَنَكُونَنَّ مِنَ الْخَاسِرِينَ
Rabbana zalamna anfusana wa in lam taghfir lana wa tarhamna lanakuanna minal-khasirin
私たちの主よ、私たちは自分自身を不当に扱いました。もしあなたが私たちを許し、慈悲を与えてくださらなければ、私たちは必ず敗者の中に入るでしょう。
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.