Sahih al-Bukhari 96
صحيح البخاري#96SahihNarrated `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
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih al-Bukhari is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 3:38