عَنْ اَلْمُغِيرَةِ بْنِ شُعْبَةَ ‏- رضى الله عنه ‏- قَالَ: { كُنْتُ مَعَ اَلنَّبِيِّ ‏- صلى الله عليه وسلم ‏-فَتَوَضَّأَ, فَأَهْوَيْتُ لِأَنْزِعَ خُفَّيْهِ, فَقَالَ:"دَعْهُمَا, فَإِنِّي أَدْخَلْتُهُمَا طَاهِرَتَيْنِ"فَمَسَحَ عَلَيْهِمَا } مُتَّفَقٌ عَلَيْه ِ 1‏ .‏‏1 ‏- صحيح.‏ رواه البخاري (206)‏، ومسلم (274)‏ (79)‏.‏
Translation
Narrated ‘Ali (rad)

If the religion were based on opinion, it would be more important to wipe over the under parts of the leather socks than the upper, but I have seen Allah’s Messenger (rad) wiping over the upper parts of his leather socks. [Reported by Abu Da’ud with good Isnad (chain of narrators)].