حَدَّثَنِي سَلَمَةُ بْنُ شَبِيبٍ، حَدَّثَنَا الْحَسَنُ بْنُ مُحَمَّدِ بْنِ أَعْيَنَ، حَدَّثَنَا مَعْقِلٌ، عَنْ أَبِي الزُّبَيْرِ، عَنْ جَابِرٍ، أَخْبَرَنِي عُمَرُ بْنُ الْخَطَّابِ، أَنَّ رَجُلاً، تَوَضَّأَ فَتَرَكَ مَوْضِعَ ظُفُرٍ عَلَى قَدَمِهِ فَأَبْصَرَهُ النَّبِيُّ صلى الله عليه وسلم فَقَالَ " ارْجِعْ فَأَحْسِنْ وُضُوءَكَ " . فَرَجَعَ ثُمَّ صَلَّى .
Jabir reported: 'Umar b. Khattab said that a person performed ablution and left a small part equal to the space of a nail (unwashed). The Apostle of Allah (PBUH) saw that and said: Go back and perform ablution well. He then went back (performed ablution well) and offered the prayer. Translation Not Available
Book Ref: Sahih Muslim Book 2 Hadith 474
Web Ref: Sahih Muslim Book 2 Hadith 243