Sahih Muslim 543
صحيح مسلم#543Sahihحَدَّثَنَا 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 (ﷺ) 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
Scholarly Authentication
The label above is the grade most of these scholars gave — one dissenting opinion no longer speaks for all of them. If any scholar calls a narration fabricated, that verdict is shown instead, whatever the others say. Each scholar's own wording:
Every narration in Sahih Muslim is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 2:10