Musannaf Ibn Abi Shayba 1:1867

Ibn ‘Uyaynah narrated to us, from ‘Asim, from Zirr, who said: I saw Safwan ibn ‘Assal al-Muradi, and he said: "What brought you?" I said: "We came seeking knowledge." He said: "Indeed, the angels lower their wings for the seeker of knowledge." He said: "And the Messenger of Allah (ﷺ), when we were on a journey, used to command us not to remove our leather socks for three days, except in the case of major ritual impurity (janabah), but not for defecation, urination, or sleep."