Sahih Muslim
Book 2: The Book of Purification
كتاب الطهارة
144 hadith in this book
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 Messenger of Allah (ﷺ) saw that and said: Go back and perform ablution well. He then went back (performed ablution well) and offered the prayer.
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 .
Hadith text, translations and grading are courtesy of Sunnah.com.