Allah's Apostle (ﷺ) saw a man who did not wash his heel and he remarked: Woe to the heels because of hell-fire.
Sahih Muslim Book 2, Hadith 40
← Previous Hadith The Messenger of Allah (ﷺ) lagged behind us on a journey. We travelled (back) and be took him; and then came the time of the afternoon prayer, and as we were going to wipe our feet he (the Holy Prophet) called out: Woe to the heels because of Hell-fire.

Sahih Muslim Book 2, Hadith 39 Next Hadith → He saw people perform ablution with the help of a water jar and he said: Complete the Wudu for i heard Abu al-Qasim (ﷺ) say: Woe to the hamstrings because of hell-fire.

Sahih Muslim Book 2, Hadith 41