One day Uthman performed a thorough ablution and then said, "I saw the Messenger of Allah ﷺ perform ablution well, then he said, 'Whoever performs ablution like this and then goes out to the mosque with nothing prompting him except the prayer, his past sins will be forgiven.'"
توضأ عثمان يوما وضوءا حسنا، ثم قال: رأيت رسول الله ﷺ توضأ فأحسن الوضوء، ثم قال: من توضأ هكذا، ثم خرج إلى المسجد لا ينهزه إلا الصلاة غفر له ما خلا من ذنبه.
Muslim narrated it in the Book of Purification (232) from Harun bin Saeed Ayli, he said, Ibn Wahb narrated to us, and Makhrama bin Bukayr informed me, from his father, from Humran. Then he mentioned something similar. His statement, "what has passed of his sin," means what has gone by of his sin.