Sayyiduna Safwan bin Assal al-Muradi (may Allah be pleased with him) narrates: The Messenger of Allah (peace and blessings be upon him) ordered us that when we were on a journey, we should not take off our leather socks for three days and nights, not because of urination, nor sleep, nor defecation, except for major ritual impurity (janabah).
Hadith Referenceالمعجم الكبير للطبراني / باب الصاد / 7343