One who performed ablution and left a place where water did not reach.
حَدَّثَنَا حَرْمَلَةُ بْنُ يَحْيَى، حَدَّثَنَا ابْنُ وَهْبٍ، ح وَحَدَّثَنَا ابْنُ حُمَيْدٍ، حَدَّثَنَا زَيْدُ بْنُ الْحُبَابِ، قَالاَ حَدَّثَنَا ابْنُ لَهِيعَةَ، عَنْ أَبِي الزُّبَيْرِ، عَنْ جَابِرٍ، عَنْ عُمَرَ بْنِ الْخَطَّابِ، قَالَ رَأَى رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ رَجُلاً تَوَضَّأَ فَتَرَكَ مَوْضِعَ الظُّفْرِ عَلَى قَدَمِهِ فَأَمَرَهُ أَنْ يُعِيدَ الْوُضُوءَ وَالصَّلاَةَ . قَالَ فَرَجَعَ .
It was narrated that 'Umar bin Khattab said: "The Messenger of Allah (ﷺ) saw a man performing ablution and he missed a spot the size of a fingernail on his foot. He commanded him to repeat the ablution and his prayer, so he did."