"The Messenger of Allah mentioned the Fire, and he turned his face away (as if seeing it), and sought refuge with Allah from it." (One of the narrators) Shu'bah said: "He did that three times, then he said: 'Protect yourselves from the Fire even with half a date, and if you cannot find that, then with a good word."'
Sunan an-Nasa'i Book 23, Hadith 119