Musnad Ahmad 627:10

'Abd al-Rahman and Ibn Ja'far narrated to us, they said: Shu'bah narrated to us, from 'Amr ibn Murrah, from Khaythamah, from 'Adi ibn Hatim, who said: The Messenger of Allah (may Allah bless him and grant him peace) mentioned the Fire. Ibn Ja'far said: He sought refuge from it and turned his face away. Then he said: "Fear the Fire, even if with half a date. If you do not find [that], then with a good word."