Sahih Muslim 543
صحيح مسلم#543SahihAmr 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
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih Muslim is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 2:10