Musnad Ahmad 1119:26

Hushaym narrated to us, he said: Dawud ibn ‘Amr informed us, from Busr ibn ‘Ubayd Allah al-Hadrami, from Abu Idris al-Khawlani, from ‘Awf ibn Malik al-Ashja‘i: "The Messenger of Allah (peace and blessings of Allah be upon him) commanded the wiping over the leather socks during the expedition of Tabuk: three days and their nights for the traveler, and one day and a night for the resident."