´Abu Sa'eed narrated regarding His (Allah's) statement:` Kal Muhl, the Prophet (s.a.w)said: 'Like boiling oil, such that when it is brought close to his face, the skin of his face will fall off into it."
Hadith Referenceسنن ترمذي / كتاب صفة جهنم عن رسول الله صلى الله عليه وسلم / 2581