وَٱلَّذِينَ إِذَا فَعَلُوا۟ فَـٰحِشَةً أَوْ ظَلَمُوٓا۟ أَنفُسَهُمْ ذَكَرُوا۟ ٱللَّهَ فَٱسْتَغْفَرُوا۟ لِذُنُوبِهِمْ وَمَن يَغْفِرُ ٱلذُّنُوبَ إِلَّا ٱللَّهُ وَلَمْ يُصِرُّوا۟ عَلَىٰ مَا فَعَلُوا۟ وَهُمْ يَعْلَمُونَ Qur’an Aal-Imran (3:135)Waallatheena itha faAAaloo fahishatan aw thalamoo anfusahum thakaroo Allaha faistaghfaroo lithunoobihim waman yaghfiru alththunooba illa Allahu walam yusirroo AAala ma faAAaloo wahum yaAAlamoona
The righteous man, when he finds he has fallen into sin or error, does not whine or despair, but asks for Allah's forgiveness, and his faith gives him hope. If he is sincere, that means that he abandons his wrong conduct and makes amends.
Sin is a sort of oppression of ourselves by ourselves. This follows from the doctrine of personal responsibility, as opposed to that of blind fate or of an angry God or gods lying in wait for revenge or injury on mankind.