Sayyiduna al-Mughirah bin Shu'bah (may Allah be pleased with him) said: The Messenger of Allah (peace and blessings be upon him) went out to relieve himself, and I followed him (peace and blessings be upon him) carrying a vessel of water. When he (peace and blessings be upon him) had finished, I began pouring water for him (peace and blessings be upon him). He (peace and blessings be upon him) washed his face. He (peace and blessings be upon him) was wearing a Roman - or Syrian - cloak; its sleeve was too narrow, so he (peace and blessings be upon him) brought his hand out from underneath it, then washed his forearms and wiped over his turban and his leather socks.
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 18070