It is narrated from Sayyiduna Mughirah bin Shu'bah (may Allah be pleased with him); he said: Whenever the Messenger of Allah (peace and blessings be upon him) went (to relieve himself), he would go far away. On one journey he (peace and blessings be upon him) went to relieve himself and said: "Bring me water for ablution." I brought him (peace and blessings be upon him) water for ablution, and he (peace and blessings be upon him) brought his hands out from under the jubbah, performed ablution, and wiped over his leather socks.
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 18187