Abdullah ibn Amr reported: We returned with the Messenger of Allah, peace and blessings be upon him, from Mecca to Medina, until we found water by the road. Some people hurried to perform ablution for afternoon prayer, by the time we reached them their heels were dry and had not been wiped with water. The Prophet said, “Woe to the heels from the Hellfire! Perform ablution thoroughly.”
Source: Ṣaḥīḥ al-Bukhārī 60, Ṣaḥīḥ Muslim 241
Grade: Muttafaqun Alayahi (authenticity agreed upon) according to Al-Bukhari and Muslim
عَنْ عَبْدِ اللَّهِ بْنِ عَمْرٍو قَالَ رَجَعْنَا مَعَ رَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ مِنْ مَكَّةَ إِلَى الْمَدِينَةِ حَتَّى إِذَا كُنَّا بِمَاءٍ بِالطَّرِيقِ تَعَجَّلَ قَوْمٌ عِنْدَ الْعَصْرِ فَتَوَضَّئُوا وَهُمْ عِجَالٌ فَانْتَهَيْنَا إِلَيْهِمْ وَأَعْقَابُهُمْ تَلُوحُ لَمْ يَمَسَّهَا الْمَاءُ فَقَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ وَيْلٌ لِلْأَعْقَابِ مِنْ النَّارِ أَسْبِغُوا الْوُضُوءَ
60 صحيح البخاري كتاب العلم باب من رفع صوته بالعلم
241 صحيح مسلم كتاب الطهارة باب وجوب غسل الرجلين بكمالهما