Zirr bin Hubaysh (may Allah have mercy on him) narrates: I came to Sayyiduna Safwan bin Assal al-Muradi (may Allah be pleased with him) and stood at his door. He came out to me and said: "What has brought you?" I said: "You are a man who has kept the company of the Prophet (peace and blessings be upon him), and I feel some doubt about wiping over the leather socks after defecation and urination. Did you hear the Messenger of Allah (peace and blessings be upon him) say anything about it?" He said: "Yes, the Messenger of Allah (peace and blessings be upon him) used to order us, when we were travelling, not to take off our leather socks for three days; but for defecation, urination or sleep (we should not take them off)."
Hadith Referenceالمعجم الكبير للطبراني / باب الصاد / 7338