once
مَا مِنْ عَبْدٍ يُذنِبُ ذَنْباً فَيُحْسِنُ الطُّهُورَ، ثُمَّ يَقُومُ فَيُصَلِّي رَكْعَتَيْنِ، ثُمَّ يَسْتَغْفِرُ اللَّهَ إِلاَّ غَفَرَ اللَّهُ لَهُ
Meaning
Any servant who commits a sin and as a result, performs ablution, prays two units of prayer (i.e. two rakAAas) and then seeks Allah’s forgiveness, Allah would forgive him.
Source and references
Hisn al-Muslim, entry 140.The reference is copied from the edition; separate editorial verification is not complete yet.
Source edition: Fortress of the Muslim. Open source ↗