It is narrated from Hazrat Abu Dharr (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) said: Do not consider any good deed insignificant, and if you cannot do anything else, then at least meet your brother with a cheerful face.
Hadith Referenceمسند احمد / مسند الأنصار رضي الله عنهم / 21519
Hadith Gradingحکم دارالسلام:صحيح لغيره، م: 2626، وهذا إسناد حسن