كتاب الأدب
1  
The Book of Good Manners
(88)
Chapter: Excellence of Meeting with a Smiling Countenance and Politeness in Speech
(88)
- باب استحباب طيبب الكلام وطلاقته الوجه عند اللقاء
Riyad as-Salihin 692
'Adi bin Hatim (May Allah be pleased with him) reported:
Messenger of Allah (ﷺ) said, "Guard yourselves against the Fire (of Hell) even if it be only with half a date-fruit (given in charity); and if you cannot afford even that, you should at least say a good word."

[Al-Bukhari and Muslim].

عن عدي بن حاتم رضي الله عنه قال‏:‏ قال رسول الله صلى الله عليه وسلم ‏ "‏اتقوا النار ولو بشق تمرة فمن لم يجد فبكلمة طيبة‏"‏ ‏(‏‏(‏متفق عليه‏)‏‏)‏ ‏.‏
Reference : Riyad as-Salihin 692
In-book reference : Book 1, Hadith 13