Zirr bin Hubaysh (may Allah have mercy on him) says: I came to Sayyiduna Safwan bin Assal (may Allah be pleased with him), and he asked: "What has brought you here so early in the morning?" I said: "The search for knowledge has brought me." He said: "Whoever does this, the angels spread their wings for him out of pleasure with what he does." I said: "I have come early in the morning to ask you about wiping over the leather socks." Sayyiduna Safwan (may Allah be pleased with him) said: I asked the Messenger of Allah (peace and blessings be upon him): "O Messenger of Allah, may I wipe over the leather socks?" He (peace and blessings be upon him) said: "Yes, three days for the traveller, he should not take them off because of defecation, urination or sleep, and one day for the resident."
Hadith Referenceالمعجم الكبير للطبراني / باب الصاد / 7318