The Messenger of Allah ﷺ mentioned the Fire, then turned his face away and sought refuge from it. Shuba mentioned that he did this three times. Then he said, "Guard yourselves against the Fire, even with half a date, and if you cannot find that, then with a kind word."
أنبأنا إسمعيل بن مسعود قال حدثنا خالد قال حدثنا شعبة أن عمرو بن مرة حدثهم عن خيثمة
ذكر رسول الله ﷺ النار فأشاح بوجهه وتعوذ منها ذكر شعبة أنه فعله ثلاث مرات ثم قال اتقوا النار ولو بشق التمرة فإن لم تجدوا فبكلمة طيبة
Bukhari narrated it in Sahih Bukhari, Manners, chapter on good speech, hadith 6023, and Muslim in Zakat, chapter etc., hadith 1016, from the hadith of Shubah, with the same chain, and it is in Kubra, Encouragement to give charity even with half a date, hadith 2334.