Hadith Q195

أَنَّ الْمَسْحَ يَقُومُ مَقَامَ غَسْلِ الْقَدَمَيْنِ، إِذَا كَانَ الْقَدَمُ بَادِيًا غَيْرَ مُغَطًّى بِالْخُفِّ، وَإِنَّ خَالِعَ الْخُفِّ وَإِنْ كَانَ لَبِسَهُ عَلَى طَهَارَةٍ، إِذَا غَسَلَ قَدَمَيْهِ كَانَ مُؤَدِّيًا لِلْفَرْضِ غَيْرَ عَاصٍ، إِلَّا أَنْ يَكُونَ تَارِكًا لِلْمَسْحِ رَغْبَةً عَنْ سُنَّةِ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ‏.‏
Wiping over both feet will be equivalent to washing them, as long as the feet are uncovered and not covered by leather socks, and if he removes the leather socks, even if he wore them in a state of purity, then when he washes both feet, he will fulfill the obligation and will not be sinful, except if he abandons wiping out of disregard for the Sunnah of the Prophet (peace be upon him), then he will be sinful.
Hadith Reference صحيح ابن خزيمه / جماع أبواب المسح على الخفين / Q195