Save your heels from the fire

عَنْ عَبْدِ اللَّهِ بْنِ عَمْرٍو، قَالَ تَخَلَّفَ عَنَّا النَّبِيُّ صلى الله عليه وسلم فِي سَفْرَةٍ سَافَرْنَاهَا، فَأَدْرَكَنَا وَقَدْ أَرْهَقَتْنَا الصَّلاَةُ وَنَحْنُ نَتَوَضَّأُ، فَجَعَلْنَا نَمْسَحُ عَلَى أَرْجُلِنَا، فَنَادَى بِأَعْلَى صَوْتِهِ ‏ “‏ وَيْلٌ لِلأَعْقَابِ مِنَ النَّارِ ‏”‏‏.‏ مَرَّتَيْنِ أَوْ ثَلاَثًا‏.‏

Narrated `Abdullah bin `Amr:

Once the Prophet (ﷺ) remained behind us in a journey. He joined us while we were performing ablution for the prayer which was over-due. We were just passing wet hands over our feet (and not washing them properly) so the Prophet (ﷺ) addressed us in a loud voice and said twice or thrice: “Save your heels from the fire.”