Zirr bin Hubaysh (may Allah have mercy on him) says: I felt a doubt in my heart about wiping over the leather socks after urination and defecation. So I came to Sayyiduna Safwan bin Assal al-Muradi (may Allah be pleased with him) and mentioned this to him. I said: "Tell me something you heard from the Messenger of Allah (peace and blessings be upon him)." He said: "He (peace and blessings be upon him) used to order us, when we were on a journey or travelling, not to take off our leather socks for three nights and their days except for major ritual impurity (janabah); but for urination, defecation or sleep (we should not take them off)."
Hadith Referenceالمعجم الكبير للطبراني / باب الصاد / 7346