(a) It is narrated from Sayyiduna Bilal (may Allah be pleased with him): I saw the Prophet (peace and blessings be upon him) performing ablution, and he (peace and blessings be upon him) wiped over the leather socks and the head-cover.
(b) It is narrated from Sayyiduna Bilal (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) performed ablution and wiped over the leather socks and the turban. (d) Ali bin Mushir and Abu Mu'awiyah narrated this from al-A'mash, and Abd al-Wahid bin Ziyad, Abu Ishaq al-Fazari and Muhammad bin Fudayl corroborated them. Al-Thawri narrated it from al-A'mash but did not mention Ka'b in his chain. Likewise Shu'bah, among others, narrated it from al-Hakam in mursal form.
Those who narrated its chain in full are thiqat (trustworthy), and Allah knows best.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 1283