Hadith 140
Hisn al-Muslim
Fortress of the Muslim (Hisn al-Muslim) · Upon committing a sin
Arabic
مَا مِنْ عَبْدٍ يُذنِبُ ذَنْباً فَيُحْسِنُ الطُّهُورَ، ثُمَّ يَقُومُ فَيُصَلِّي رَكْعَتَيْنِ، ثُمَّ يَسْتَغْفِرُ اللَّهَ إِلاَّ غَفَرَ اللَّهُ لَهُ
English translation
There is not any slave of Allah who commits a sin, then he perfects his purification and stands to pray two Rak'ahs of prayer, then seeks Allah's forgiveness, except that Allah will forgive him. Reference: Abu Dawud 2/86, At-Tirmidhi 2/257. Al-Albani graded it authentic in Sahih Abu Dawud 1/283.