It is narrated from Sayyiduna al-Mughirah bin Shu'bah (may Allah be pleased with him) that he (peace and blessings be upon him) "used to wipe over the top and bottom of the khuffs (leather socks)."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 1377
Sayyiduna al-Mughirah bin Shu'bah (may Allah be pleased with him) said: During the Battle of Tabuk I placed water for the Prophet (peace and blessings be upon him) (for ablution), and he (peace and blessings be upon him) wiped over the top and bottom of the khuff (leather sock).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 1378
(a) Al-Walid narrated it with the same meaning, saying that it is reported from Raja' bin Haywah. (b) Imam Abu Dawud (may Allah have mercy on him) said: It is said that Thawr did not hear this hadith from Raja'. (c) Thawr said: I was told from Raja' bin Haywah, from the scribe of al-Mughirah, from the Prophet (peace and blessings be upon him), as a mursal report, and there is no mention of Sayyiduna al-Mughirah (may Allah be pleased with him) in it. The Shaykh said: Abu Isa (al-Tirmidhi) mentioned it likewise from al-Bukhari and Abu Zur'ah al-Razi.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 1380
It is narrated from Ibn Shihab (may Allah have mercy on him): The one who wipes should place one hand on top of the khuff (leather sock) and one hand beneath the khuff, then wipe.
(b) Imam Malik (may Allah have mercy on him) said: Of what I have heard regarding wiping over the khuffs, this seems the most correct to me.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 1383