Hadithcore
Jami` at-Tirmidhi, 2005
sahih· Darussalam

Abu Wahb narrated that :

'Abdullah bin Al-Mubarak explained good character, and then he said: "It is a smiling face, doing one's best in good, and refraining from harm."

حَدَّثَنَا أَحْمَدُ بْنُ عَبْدَةَ الضَّبِّيُّ، حَدَّثَنَا أَبُو وَهْبٍ، عَنْ عَبْدِ اللَّهِ بْنِ الْمُبَارَكِ، أَنَّهُ وَصَفَ حُسْنَ الْخُلُقِ فَقَالَ هُوَ بَسْطُ الْوَجْهِ وَبَذْلُ الْمَعْرُوفِ وَكَفُّ الأَذَى ‏.‏

References2 variants
In-Book Reference
Book 27, Hadith 111
English Reference
Vol. 4, Book 1, Hadith 2005