It is narrated from Sayyiduna Jarir (may Allah be pleased with him) that the Prophet of Allah (peace and blessings be upon him) went into a thicket and relieved himself. Sayyiduna Jarir (may Allah be pleased with him) brought him a vessel of water, and he (peace and blessings be upon him) cleaned himself (istinja), wiped his hand with earth, then washed his face and forearms, and wiped over his head and over his leather socks. I said: O Prophet of Allah, your feet? He (peace and blessings be upon him) said: "I put them in (the socks) while they were in a state of purity."
Hadith Referenceالمعجم الكبير للطبراني / باب الجيم / 2380