حَدَّثَنَا عَبْدُ بْنُ حُمَيْدٍ، وَحَجَّاجُ بْنُ الشَّاعِرِ، كِلاَهُمَا عَنْ أَبِي الْوَلِيدِ، قَالَ عَبْدٌ حَدَّثَنِي أَبُو الْوَلِيدِ، حَدَّثَنَا إِسْحَاقُ بْنُ سَعِيدِ بْنِ عَمْرِو بْنِ سَعِيدِ بْنِ الْعَاصِ، حَدَّثَنِي أَبِي، عَنْ أَبِيهِ، قَالَ كُنْتُ عِنْدَ عُثْمَانَ فَدَعَا بِطَهُورٍ فَقَالَ سَمِعْتُ رَسُولَ اللَّهِ صلى الله عليه وسلم يَقُولُ ‏"‏ مَا مِنِ امْرِئٍ مُسْلِمٍ تَحْضُرُهُ صَلاَةٌ مَكْتُوبَةٌ فَيُحْسِنُ وُضُوءَهَا وَخُشُوعَهَا وَرُكُوعَهَا إِلاَّ كَانَتْ كَفَّارَةً لِمَا قَبْلَهَا مِنَ الذُّنُوبِ مَا لَمْ يُؤْتِ كَبِيرَةً وَذَلِكَ الدَّهْرَ كُلَّهُ ‏"‏ ‏.‏

'Amr b Sa'id b al-As reported: I was with Uthman, and he called for ablution water and said: I heard Allah's Messenger (PBUH) say: When the time for a prescribed prayer comes, if any Muslim performs ablution well and offers his prayer with humility and bowing, it will be an expiation for his past sins, so long as he has not committed a major sin; and this applies for all times. Translation Not Available

Book Ref: Sahih Muslim Book 2 Hadith 441
Web Ref:  Sahih Muslim Book 2 Hadith 228