Buraydah (radiallahu anhu) says, "Najaashi sent two simple black coloured socks as a gift to Sayyidina Rasulullah sallallahu alaihe wasallam. He wore these and made mash over them after performing wudu". (DE)
English reference (DE): Book 9, Hadith 69 (DE)
Arabic reference (DE): Book 10, Hadith 73 (DE)