The Book Pertaining to Paradise, Its Description, Its Bounties and Its Intimates (Kitab Al-Jannat wa Sifat Na'imiha wa Ahliha)
Muslim :: Book 40 : Hadith 6850
This hadith has been transmitted on the authority of Ibn 'Umar but with a slight variation of wording (and the words are):" One of them would be completely submerged in perspiration up to half of his ears."