كتاب الفضائل
8  
The Book of Virtues
(185)
Chapter: The Merits of Ablutions (Wudu')
(185)
- باب فضل الوضوء‏:‏
Riyad as-Salihin 1027
'Uthman bin 'Affan (May Allah be pleased with him) reported:
I saw the Messenger of Allah (ﷺ) performing Wudu' the way I have just done it and said, "He who performs Wudu' like this, his previous sins will be forgiven and his Salat and walking to the mosque will be considered as supererogatory act of worship."

[Muslim].

وعنه قال‏:‏ رأيت رسول الله صلى الله عليه وسلم يتوضأ مثل وضوئي هذا ثم قال‏:‏ ‏ "‏من توضأ هكذا، غفر له ما تقدم من ذنبه، وكانت صلاته ومشيه إلى المسجد نافلة‏"‏ ‏(‏‏(‏رواه مسلم‏)‏‏)‏‏.‏
Reference : Riyad as-Salihin 1027
In-book reference : Book 8, Hadith 37