Humran bin Abban reported,

We were with Uthman bin Affan when he called for water and performed ablution. After completing his ablution, he smiled and asked, "Do you know why I laughed?"He then said, "The Messenger of Allah ﷺ performed ablution as I have just done, then he smiled and asked, 'Do you know why I laughed?'"We replied, "Allah and His Messenger know best."He said, "When a servant performs ablution and does it well, then enters into his prayer and completes it properly, he emerges from his prayer free of sins, just as he emerged from his mother's womb."

حدثنا إسحاق بن يوسف حدثنا عوف الأعرابي عن معبد الجهنى

عن حمران بن أبان قال

كنا عند عثمان بن عفان رضي الله عنه فدعا بماء فتوضأ فلما فرغ من وضوئه تبسم فقال هل تدرون مما ضحكت قال فقال توضأ رسول الله ﷺ كما توضأت ثم تبسم ثم قال هل تدرون مم ضحكت قال قلنا الله ورسوله أعلم قال إن العبد إذا توضأ فأتم وضوءه ثم دخل في صلاته فأتم صلاته خرج من صلاته كما خرج من بطن أمه من الذنوب