Sahih Bukhari Volume 1, Book 4, Hadith 206

حَدَّثَنَا أَبُو نُعَيْمٍ، قَالَ حَدَّثَنَا زَكَرِيَّاءُ، عَنْ عَامِرٍ، عَنْ عُرْوَةَ بْنِ الْمُغِيرَةِ، عَنْ أَبِيهِ، قَالَ كُنْتُ مَعَ النَّبِيِّ صلى الله عليه وسلم فِي سَفَرٍ، فَأَهْوَيْتُ لأَنْزِعَ خُفَّيْهِ فَقَالَ ‏"‏ دَعْهُمَا، فَإِنِّي أَدْخَلْتُهُمَا طَاهِرَتَيْنِ ‏"‏‏.‏ فَمَسَحَ عَلَيْهِمَا

Narrated By 'Urwa bin Al-Mughira : My father said, "Once I was in the company of the Prophet on a journey and I dashed to take off his Khuffs. He ordered me to leave them as he had put them after performing ablution. So he passed wet hands or them.