My father related to me from his father, who said:I was with Uthman bin Affan when he called for water for ablution and said, "I heard the Messenger of Allah ﷺ say, 'There is no Muslim who, when the time of an obligatory prayer arrives, performs its ablution well and observes its humility and bowing properly, except that it serves as an expiation for the sins he committed before it, so long as he does not commit a major sin. And this applies for all time.'"
حدثني أبي، عن أبيه قال: كنت عند عثمان بن عفان، فدعا بطهور فقال: سمعت رسول الله ﷺ يقول: ما من امرئ مسلم تحضره صلاة مكتوبة، فيحسن وضوءها وخشوعها وركوعها إلا كانت كفارة لما قبلها من الذنوب، ما لم يؤت كبيرة، وذلك الدهر كله.