Mukhtasar Bukhari (Abridged) 156 — Do not remove socks to wash feet if

Narrated Sayyiduna Mughira (may Allah be pleased with him): I was with the Prophet (peace and blessings of Allah be upon him) on a journey, so when it was time for ablution, I intended to remove both of his leather socks. The Prophet (peace and blessings of Allah be upon him) said, "Leave them, for I put them on while my feet were in a state of purity." Then he wiped over them.