Urwah bin al-Mughirah bin Shu'bah narrates from his father (Sayyiduna al-Mughirah, may Allah be pleased with him) that he said: I was with the Prophet (peace and blessings be upon him) on a journey, and he (peace and blessings be upon him) said: "Do you have water with you?" I said: Yes. He (peace and blessings be upon him) dismounted from his mount, then he (peace and blessings be upon him) walked on until he disappeared from me in the darkness of the night. Then he came back, and I poured water over him (peace and blessings be upon him) from the vessel. He (peace and blessings be upon him) washed his hands and face. He (peace and blessings be upon him) was wearing a woollen cloak, and he (peace and blessings be upon him) could not bring his forearms out of it, so he brought them out from beneath his cloak, washed them and wiped his head. Then I bent down to take off the leather socks of the Prophet (peace and blessings be upon him), but he (peace and blessings be upon him) said: "Leave them, for I put them on while in a state of purity." Then he (peace and blessings be upon him) wiped over them.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 1336