A person came to the Messenger of Allah ﷺ. He performed ablution and left a small part equal to the space of a nail upon his foot. The Messenger of Allah ﷺ said to him : Go back and perform ablution well. Abu Dawud said: This tradition is not known through Jarir b. Hazim. It was transmitted only by Ibn Wahab. Another version adds the wording : “ Go back and perform the ablution well.” (Using translation from Abū Dāʾūd 173)
أَنَّ رَجُلًا جَاءَ إِلَى النَّبِيِّ ﷺ قَدْ تَوَضَّأَ وَتَرَكَ عَلَى قَدَمِهِ مِثْلَ مَوْضِعِ الظُّفُرِ فَقَالَ لَهُ رَسُولُ اللهِ ﷺ ارْجِعْ فَأَحْسِنْ وُضُوءَكَ