Musnad Ahmad 56
It was narrated that Asma' bin [sic] al-Hakam al-Fazari said:
I heard ‘Ali say: If I heard a hadeeth from the Messenger of Allah (ﷺ), Allah benefitted me as He willed thereby. If someone else told me something from him I would ask him to swear, and if he swore I would believe him. Abu Bakr told me - and Abu Bakr told the truth - that he heard the Prophet (ﷺ) say: `There is no believer who commits a sin, then does wudoo` and does it well and prays two rak'ahs and asks Allah, may He be glorified and exalted, for forgiveness but Allah will forgive him.` Then he recited the verse: `And those who, when they have committed Fahishah (illegal sexual intercourse) or wronged themselves...` (Al ‘Imran 3:135).
حَدَّثَنَا أَبُو كَامِلٍ، حَدَّثَنَا أَبُو عَوَانَةَ، حَدَّثَنَا عُثْمَانُ بْنُ أَبِي زُرْعَةَ، عَنْ عَلِيِّ بْنِ رَبِيعَةَ، عَنْ أَسْمَاءَ بْنِ الْحَكَمِ الْفَزَارِيِّ، قَالَ سَمِعْتُ عَلِيًّا، كَرَّمَ اللَّهُ وَجْهَهُ قَالَ كُنْتُ إِذَا سَمِعْتُ مِنْ رَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ حَدِيثًا نَفَعَنِي اللَّهُ بِهِ بِمَا شَاءَ أَنْ يَنْفَعَنِي مِنْهُ وَإِذَا حَدَّثَنِي غَيْرُهُ اسْتَحْلَفْتُهُ فَإِذَا حَلَفَ لِي صَدَّقْتُهُ وَحَدَّثَنِي أَبُو بَكْرٍ وَصَدَقَ أَبُو بَكْرٍ قَالَ قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ مَا مِنْ عَبْدٍ مُؤْمِنٍ يُذْنِبُ ذَنْبًا فَيَتَوَضَّأُ فَيُحْسِنُ الطُّهُورَ ثُمَّ يُصَلِّي رَكْعَتَيْنِ فَيَسْتَغْفِرُ اللَّهَ تَعَالَى إِلَّا غَفَرَ اللَّهُ لَهُ ثُمَّ تَلَا ‏{‏وَالَّذِينَ إِذَا فَعَلُوا فَاحِشَةً أَوْ ظَلَمُوا أَنْفُسَهُمْ‏}‏‏.‏