SURAH AL-BAQARAH: 37

Part 3

When asked as to what a person who has committed a sin should do, great scholars and sufis have said that he should do exactly what his first parents Adam and Hawwa علیہما السّلام did - that he should feel genuine remorse for his deed, should vow never to indulge in that sin again, and pray to Allah for forgiveness as they had,

 رَبَّنَا ظَلَمۡنَآ أَنفُسَنَا وَإِن لَّمۡ تَغۡفِرۡ لَنَا وَتَرۡحَمۡنَا لَنَكُونَنَّ مِنَ ٱلۡخَـٰسِرِينَ 

"Our Lord, we have wronged ourselves, and if You do not forgive us and have mercy upon us, we will surely be among the losers." (7:23)

Similarly. Hazrat Musa (Moses) علیہ السلام made the following prayer:

   رَبِّ إِنِّى ظَلَمۡتُ نَفۡسِى فَٱغۡفِرۡ لِى فَغَفَرَلَهُ

  "My Lord, I have wronged myself. Please forgive me." (28:16)

And when Yunus (Jonas) علیہ السلام made a mistake he prayed: 

 لَّآ إِلَـٰهَ إِلَّآ أَنتَ سُبۡحَـٰنَكَ إِنِّى ڪُنتُ مِنَ ٱلظَّـٰلِمِينَ

"There is no God but You. Pure are You. I have certainly become one of the unjust." (21:87) (Qurtubi)

From Ma'ariful Quran, by Mufti Muhammad Shafi RE