Musnad Ahmad 493
It was narrated from Humran, the freed slave of `Uthman (رضي الله عنه) that `Uthman did wudoo’ in al-Maqa`id, he washed each part of the body three times and said:
I heard the Messenger of Allah (ﷺ) say:  “Whoever does wudoo’ as I have done then gets up to pray, his sins will fall away, i.e., from his face, his hands, his feet and his head.`
حَدَّثَنَا سُفْيَانُ بْنُ عُيَيْنَةَ، عَنْ هِشَامٍ، عَنْ أَبِيهِ، عَنْ حُمْرَانَ، مَوْلَى عُثْمَانَ رَضِيَ اللَّهُ عَنْهُ أَنَّ عُثْمَانَ تَوَضَّأَ بِالْمَقَاعِدِ فَغَسَلَ ثَلَاثًا ثَلَاثًا وَقَالَ سَمِعْتُ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يَقُولُ مَنْ تَوَضَّأَ وُضُوئِي هَذَا ثُمَّ قَامَ إِلَى الصَّلَاةِ سَقَطَتْ خَطَايَاهُ يَعْنِي مِنْ وَجْهِهِ وَيَدَيْهِ وَرِجْلَيْهِ وَرَأْسِهِ‏.‏