Sunan an-Nasa'i 111
سنن النسائي#111SahihIt was narrated that 'Abdullah bin 'Amr said:"The Messenger of Allah (ﷺ) saw some people whose heels were still dry, so he said: 'Woe to the heels from the Fire. Perform Wudu' properly
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Abu GhuddahSahih
Al-AlbaniSahih
Zubair Ali ZaiSahih Muslim
In-book reference: 1:111