Sahih al-Bukhari 6563
Narrated `Adi bin Hatim:
The Prophet (ﷺ) mentioned the Fire and turned his face aside and asked for Allah's protection from it, and 
then again he mentioned the Fire and turned his face aside and asked for Allah's protection from it and 
said, "Protect yourselves from the Hell-Fire, even if with one half of a date, and he who cannot afford 
that, then (let him do so) by (saying) a good, pleasant word."
حَدَّثَنَا سُلَيْمَانُ بْنُ حَرْبٍ، حَدَّثَنَا شُعْبَةُ، عَنْ عَمْرٍو، عَنْ خَيْثَمَةَ، عَنْ عَدِيِّ بْنِ حَاتِمٍ، أَنَّ النَّبِيَّ صلى الله عليه وسلم ذَكَرَ النَّارَ فَأَشَاحَ بِوَجْهِهِ فَتَعَوَّذَ مِنْهَا، ثُمَّ ذَكَرَ النَّارَ فَأَشَاحَ بِوَجْهِهِ فَتَعَوَّذَ مِنْهَا، ثُمَّ قَالَ ‏
"‏ اتَّقُوا النَّارَ وَلَوْ بِشِقِّ تَمْرَةٍ، فَمَنْ لَمْ يَجِدْ فَبِكَلِمَةٍ طَيِّبَةٍ ‏"‏‏.‏