Ablutions (Wudu')
Bukhari :: Book 1 :: Volume 4 :: Hadith 166
Narrated Muhammad Ibn Ziyad:
I heard Abu Huraira saying as he passed by us while the people were performing ablution from a utensil containing water, "Perform ablution perfectly and thoroughly for Abul-Qasim (the Prophet) said, 'Save your heels from the Hell-fire.' "