Sahih Muslim 227a
Humran. the freed slave of 'Uthman. said:
I heard from 'Uthman b. 'Affan and he was in the courtyard of the mosque, when the Mu'adhdhin (announcer of the prayer) came to him at the time of afternoon prayer. So the ('Uthman) called for the ablution water and performed ablution and then said: By Allah, I am narrating to you a hadith. If there were not a verse in the Book of Allah, I would have never narrated it to you. I heard Allah's Messenger (ﷺ) say: If a Muslim performs ablution and does it well and offers prayer, all his (sins) daring the period from one prayer to another would be pardoned by Allah.
حَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، وَعُثْمَانُ بْنُ مُحَمَّدِ بْنِ أَبِي شَيْبَةَ، وَإِسْحَاقُ بْنُ إِبْرَاهِيمَ الْحَنْظَلِيُّ، - وَاللَّفْظُ لِقُتَيْبَةَ - قَالَ إِسْحَاقُ أَخْبَرَنَا وَقَالَ الآخَرَانِ، حَدَّثَنَا جَرِيرٌ، عَنْ هِشَامِ بْنِ عُرْوَةَ، عَنْ أَبِيهِ، عَنْ حُمْرَانَ، مَوْلَى عُثْمَانَ قَالَ سَمِعْتُ عُثْمَانَ بْنَ عَفَّانَ، وَهُوَ بِفِنَاءِ الْمَسْجِدِ فَجَاءَهُ الْمُؤَذِّنُ عِنْدَ الْعَصْرِ فَدَعَا بِوَضُوءٍ فَتَوَضَّأَ ثُمَّ قَالَ وَاللَّهِ لأُحَدِّثَنَّكُمْ حَدِيثًا لَوْلاَ آيَةٌ فِي كِتَابِ اللَّهِ مَا حَدَّثْتُكُمْ إِنِّي سَمِعْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم يَقُولُ ‏
"‏ لاَ يَتَوَضَّأُ رَجُلٌ مُسْلِمٌ فَيُحْسِنُ الْوُضُوءَ فَيُصَلِّي صَلاَةً إِلاَّ غَفَرَ اللَّهُ لَهُ مَا بَيْنَهُ وَبَيْنَ الصَّلاَةِ الَّتِي تَلِيهَا ‏"‏ ‏.‏