بسم الله الرحمن الرحيم

“Whoever believes in Allah and the Last day then let him speak good or remain silent”
Bukhaari & Muslim

And the Messenger of Allah – صلى الله عليه و سلم -said

“A good word is charity”
Saheeh Al Jaami’ As Sagheer: Al-Albani

“The majority of sins of the children of Aadam (عليه الصلاة و السلام) are because of his tongue.”
Saheeh Al Jaami’ As Sagheer: Al-Albani

Imaam An-Nawawi commented on the first hadeeth *:

This hadeeth is clear that it is befitting that you do not speak except if the speech is good and that there is a clear benefit. And when there is doubt (whether there is) a clear benefit then you do not speak.

Know that it is befitting for every person (who has reached the age of accountability and is sane) that he preserves his tongue from all speech except if the speech is clear in its benefit.

And when the benefit in speaking or leaving speech is equal; then the Sunnah is to refrain from speaking. Because it is possible that permissible speech can be swept along and become impermissible or disliked speech and this is the norm in most cases; and there is nothing that can equal safety.

* Riyaadhus Saaliheen 347-348