Sahih Bukhari Volume 007, Book 072, Hadith Number 680.

Narrated By Abu Huraira : The Prophet (or 'Abul Qasim) said, "While a man was walking, clad in a two-piece garment and proud of himself with his hair well-combed, suddenly Allah made him sink into the earth and he will go on sinking into it till the Day of Resurrection.