The Messenger of Allah (ﷺ) said: Woe to the heels because of hell-fire.
Sahih Muslim Book 2, Hadith 42
← Previous 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 Next Hadith → 'Umar b. Khattab said that a person performed ablution and left a small part equal to the space of a nail (unwashed). The Apostle of Allah (ﷺ) saw that and said: Go back and perform ablution well. He then went back (performed ablution well) and offered the prayer.

Sahih Muslim Book 2, Hadith 43