Chapter 3: Knowledge
Narrated 'Abdullah bin 'Amr: Once Allah' s Messenger (ﷺ) remained behind us in a journey. He joined us while we were performing
ablution for the 'Asr prayer which was over-due. We were just passing wet hands over our feet (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."
Sahih al-Bukhari 96