Sahih Bukhari Volume 1, Book 8, Hadith 363

حَدَّثَنَا يَحْيَى، قَالَ حَدَّثَنَا أَبُو مُعَاوِيَةَ، عَنِ الأَعْمَشِ، عَنْ مُسْلِمٍ، عَنْ مَسْرُوقٍ، عَنْ مُغِيرَةَ بْنِ شُعْبَةَ، قَالَ كُنْتُ مَعَ النَّبِيِّ صلى الله عليه وسلم فِي سَفَرٍ فَقَالَ ‏"‏ يَا مُغِيرَةُ، خُذِ الإِدَاوَةَ ‏"‏‏.‏ فَأَخَذْتُهَا فَانْطَلَقَ رَسُولُ اللَّهِ صلى الله عليه وسلم حَتَّى تَوَارَى عَنِّي فَقَضَى حَاجَتَهُ، وَعَلَيْهِ جُبَّةٌ شَأْمِيَّةٌ، فَذَهَبَ لِيُخْرِجَ يَدَهُ مِنْ كُمِّهَا فَضَاقَتْ، فَأَخْرَجَ يَدَهُ مِنْ أَسْفَلِهَا، فَصَبَبْتُ عَلَيْهِ فَتَوَضَّأَ وُضُوءَهُ لِلصَّلاَةِ، وَمَسَحَ عَلَى خُفَّيْهِ، ثُمَّ صَلَّى‏

Narrated By Mughira bin Shu'ba : Once I was travelling with the Prophet and he said, "O Mughira! take this container of water." I took it and Allah's Apostle went far away till he disappeared. He answered the call of nature and was wearing a Syrian cloak. He tried to take out his hands from its sleeve but it was very tight so he took out his hands from under it. I poured water and he performed ablution like that for prayers and passed his wet hands over his Khuff (leather socks) and then prayed.