The Book of Purification
2/9. Chapter:
The obligation of washing the feet completely
Sahih Muslim
حَدَّثَنَا عَبْدُ الرَّحْمَنِ بْنُ سَلاَّمٍ الْجُمَحِيُّ، حَدَّثَنَا الرَّبِيعُ، - يَعْنِي ابْنَ مُسْلِمٍ - عَنْ مُحَمَّدٍ، - وَهُوَ ابْنُ زِيَادٍ - عَنْ أَبِي هُرَيْرَةَ، أَنَّ النَّبِيَّ صلى الله عليه وسلم رَأَى رَجُلاً لَمْ يَغْسِلْ عَقِبَيْهِ فَقَالَ " وَيْلٌ لِلأَعْقَابِ مِنَ النَّارِ " .
Abu Huraira reported: Allah's Apostle (ﷺ) saw a man who did not wash his heel and he remarked: Woe to the heels because of hell-fire.
Reference : Sahih Muslim 242aIn-book reference : Book 2, Hadith 40USC-MSA web (English) reference : Book 2, Hadith 471