Musnad Ahmad 415
It was narrated from Aban from `Uthman (رضي الله عنه) that he called for water and did wudoo`:
he rinsed his mouth and nose, then he washed his face three times, his arms three times each, and wiped his head and the tops of his feet, then he smiled and said to his companions: Aren`t you going to ask me what made me smile? They said: What made you smile, O Ameer al-Mu`mineen? He said: I saw the Messenger of Allah (ﷺ)  call for water near this spot, then he did wudoo’ as I have done it, then he smiled and said: `Aren`t you going to ask me what made me smile?` They said: What made you smile, O Messenger of Allah (ﷺ)? He said: “If a person calls for (water for) wudoo’, then he washes his face, Allah will remove from him every sin that he committed with his face; when he washes his arms, the same applies; when he wipes his head, the same applies; when he purifies his feet, the same applies.”
حَدَّثَنَا مُحَمَّدُ بْنُ جَعْفَرٍ، حَدَّثَنَا سَعِيدٌ، عَنْ قَتَادَةَ، عَنْ مُسْلِمِ بْنِ يَسَارٍ، عَنْ حُمْرَانَ بْنِ أَبَانَ، عَنْ عُثْمَانَ بْنِ عَفَّانَ، رَضِيَ اللَّهُ عَنْهُ أَنَّهُ دَعَا بِمَاءٍ فَتَوَضَّأَ وَمَضْمَضَ وَاسْتَنْشَقَ ثُمَّ غَسَلَ وَجْهَهُ ثَلَاثًا وَذِرَاعَيْهِ ثَلَاثًا ثَلَاثًا وَمَسَحَ بِرَأْسِهِ وَظَهْرِ قَدَمَيْهِ ثُمَّ ضَحِكَ فَقَالَ لِأَصْحَابِهِ أَلَا تَسْأَلُونِي عَمَّا أَضْحَكَنِي فَقَالُوا مِمَّ ضَحِكْتَ يَا أَمِيرَ الْمُؤْمِنِينَ قَالَ رَأَيْتُ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ دَعَا بِمَاءٍ قَرِيبًا مِنْ هَذِهِ الْبُقْعَةِ فَتَوَضَّأَ كَمَا تَوَضَّأْتُ ثُمَّ ضَحِكَ فَقَالَ أَلَا تَسْأَلُونِي مَا أَضْحَكَنِي فَقَالُوا مَا أَضْحَكَكَ يَا رَسُولَ اللَّهِ فَقَالَ إِنَّ الْعَبْدَ إِذَا دَعَا بِوَضُوءٍ فَغَسَلَ وَجْهَهُ حَطَّ اللَّهُ عَنْهُ كُلَّ خَطِيئَةٍ أَصَابَهَا بِوَجْهِهِ فَإِذَا غَسَلَ ذِرَاعَيْهِ كَانَ كَذَلِكَ وَإِنْ مَسَحَ بِرَأْسِهِ كَانَ كَذَلِكَ وَإِذَا طَهَّرَ قَدَمَيْهِ كَانَ كَذَلِكَ‏.‏