He informed him that the Messenger of Allah ﷺ saw a man who had performed ablution for the noon prayer but had left the area of a fingernail's space on the top of his foot unwashed. The Messenger of Allah ﷺ noticed it and said, "Go back and perform your ablution properly." So the man went back, performed ablution again, and then prayed.
حدثنا الحسن حدثنا ابن لهيعة حدثنا أبو الزبير عن جابر أن
أخبره أن رسول الله ﷺ رأى رجلا توضأ لصلاة الظهر فترك موضع ظفر على ظهر قدمه فأبصره رسول الله ﷺ فقال ارجع فأحسن وضوءك فرجع فتوضأ ثم صلى