Abu Dharr (May Allah be pleased with him) reported:
Messenger of Allah (ﷺ) said, "Do not disdain a good deed, (no matter how small it may seem) even if it is your meeting with your (Muslim) brother with a cheerful face."[Muslim]. (FR)
App reference (FR): Book 2, Hadith 15 (FR)
Arabic/English book reference (FR): Book 2, Hadith 695 (FR)