Zirr bin Hubaysh (may Allah have mercy on him) narrates: I said to Sayyiduna Safwan bin Assal (may Allah be pleased with him): "I feel some doubt about wiping over the leather socks. Did you hear anything from the Messenger of Allah (peace and blessings be upon him) about it?" He said: "Yes, he (peace and blessings be upon him) used to order us, when we were on a journey, not to take off the leather socks for three days except for major ritual impurity (janabah); but for sleep, defecation and urination (we should not take them off)."
Hadith Referenceالمعجم الكبير للطبراني / باب الصاد / 7353