SMILE! IT’S SUNNAH

The magical effect that a smile has on others is well-known. Allaah The Almighty created mankind with an innate inclination to love those who are friendly. A person who meets others with a smile drives away their anxiety and troubles and spreads tranquility and comfort. This is because smiling is a commendable characteristic, and the one who smiles is complimented.
The Prophet, sallallaahu ‘alayhi wa sallam, was known to have a pleasant smiling face. In fact, it became a part of his character. The people who socialized with him recognized this characteristic in him. ‘Abdullaah ibnul-Haarith ibn Hazm, RadhiAllahu Anhu, said: “I never saw anyone smile more than the Prophet, sallallaahu ‘alayhi wa sallam.” [At-Tirmithi] Jareer ibn ‘Abdullaah Al-Bajali, RadhiAllahu Anhu, said: “The Prophet, sallallaahu ‘alayhi wa sallam, did not keep himself from me ever since I embraced Islam, and whenever he saw me he received me with a smile.” [Al-Bukhaari and Muslim] This was how the Prophet, sallallaahu ‘alayhi wa sallam, gained the affection of people, and this made them more ready to accept the truth that he proclaimed.
This was stressed by the saying of ‘Aa’ishah, RadhiAllahu Anhula, “I never saw the Messenger of Allaah, sallallaahu ‘alayhi wa sallam, laughing to the extent that I could see his uvula (the fleshy lobe at the back of his palate) – he would only smile.” [Al-Bukhaari and Muslim]