SHAFAQNA – It is narrated that, if speech is silver then silence is gold. Because it has been mentioned in narrations that most of the residents of the hell, enter there with their tongues. The learned scholars say: Because the sins of the tongue is not comparable with other parts of the body like, eye, ear, hand or leg therefore, controlling tongue is the first advice given to those who want to train themselves according to divine manners; meaning be careful what comes out of your mouth.
Another narration says: Tongue is like a dog with rabies, like a dog that bites others all the time and this will lead to adversity because many sins originates from the tongue. It is narrated from Imam Baqer (AS) who said: If all the bad deeds are gathered in one house, the lock of the door of that house is lying. Meaning, lying which is one of the sins of the tongue, is also the key to many other bad deeds.
Source: Website of the Ayatollah Mojtaba Tehrani