Musnad Abu Ya'la al-Mawsili 3:4

Abu Khaythama narrated to us, Abu Mu'awiyah narrated to us, al-A'mash narrated to us, from al-Hakam, from al-Qasim ibn Mukhaymira, from Shurayh ibn Hani, who said: I asked Aisha about wiping over the leather socks (khuffayn). She said: "Go to Ali and ask him, for he was more knowledgeable about that than I." So I went to Ali and asked him about the wiping. He said: "The Messenger of Allah (peace and blessings of Allah be upon him) used to command us that the resident should wipe for a day and a night, and the traveler for three days."