Sahih Bukhari
Good Manners and Form (Al-Adab)
Volume: 008 / Book Number: 073 / Hadith Number: 52
Narrated 'Adi bin Hatim:
The Prophet mentioned the (Hell) Fire and sought refuge (with Allah) from it, and turned his face to the other side. He mentioned the (Hell) Fire again and took refuge (with Allah) from it and turned his face to the other side. (Shu'ba, the sub-narrator, said, "I have no doubt that the Prophet repeated it twice.") The Prophet then said, "(O people!) Save yourselves from the (Hell) Fire even if with one half of a date fruit (given in charity), and if this is not available, then (save yourselves) by saying a good pleasant friendly word."