”(A true believer) speaks less and is truthful in his speech…”[89]
Thus, the forty-sixth characteristic of a true believer is that he speaks less. In relation to one speaking less, we have numerous traditions which show the importance of this trait since it is through the tongue that numerous sins are committed.
This instrument of sinning is available everywhere, at all times and is very easy to make use of. However as for other sins, there are (other) ways through which they are done and they have a specific time and place in which they can be performed - however the sins of the tongue are the most dangerous ones.
In addition, the tongue is that instrument through which (at least) thirty of the major sins are committed. However for sins such as drinking alcohol or gambling, there is only one instrument of the body at use when performing that sin. Therefore in order to counter the dangers of the tongue, we have been commanded to speak very less - rather - we must observe silence as much as possible.
In relation to the importance of maintaining silence and speaking less, we have many traditions of which, we narrate five short ones from the book Mizanul Hikmah. Contained within each of these tradition is one point in relation to the benefit of not speaking much.
1. Silence - The First Step in the Worship of Allah (SwT):

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The Messenger of Allah (S) has said, “Silence is the first form of worship (of Allah).”[90]
Scholars who write and speak about attaining spiritual proximity to Allah (SwT) first off advise their students to observe silence and speak less.
From the point of view of the general (Muslim) population, the person who drinks as much as one drop of alcohol when he is inside a Masjid is a very despicable person - however these same people (who think that this act is despicable) will spend the whole day - from morning to night - in that same sacred place indulging in backbiting, lying, and leveling false accusations against other people and they will not even tire out in the least! This is because the detestability of the sins of the tongue are very less in the eyes of the people and they do not see such things as being bad to perform. But rather, this is one of the most dangerous things since as a sin gets more and more despicable, the more and more people will try to stay away from that sin, but the sins of the tongue are not even considered as anything bad by the common people.
2. Silence Keeps Shaitan Far Away:

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The Messenger of Allah (S) has said, “I advise you to prolong keeping quiet since this act repels Shaitan.”[91]
When a person speaks a lot, Shaitan is around him, busy listening to what he is saying and at any moment, it is possible that the person's tongue may begin to swerve and one may start to speak bad things. Sometimes the bad feelings, feuds and enmities which take place within families are due to the useless talk that Shaitan enters into.
3. Silence - The Best Protector:

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Imam 'Ali (as) has said, “There is no protector better for protecting (a person) than silence.”[92]
We see that sometimes the tongue is the reason why a person is even killed. In the face of jealousy, enmity and other Shaitanic things, remaining quiet is the best protector for a person.
4. Silence - The Source of Dignity:

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Imam 'Ali (as) has said, “Silence clothes a person with the robes of dignity and reduces the need to always ask for forgiveness”[93]
Those people who speak too much in gatherings are less dignified that others. Thus, it is through maintaining silence that the honour of a person is increased.
In addition to this, a person does not need to always ask for forgiveness because when a person speaks too much, he will fall into the trap of saying things which may necessitate him to apologize more often. This will lessen his spiritual worth - and if he does not ask for forgiveness, then his worth will be lessened. Thus, if he always has to ask others for forgiveness, then his dignity is lowered and similarly, his honour is also lowered in the eyes of the people since he is always forced to ask others for forgiveness for his errors.
5. Silence - The Garden of Contemplation and Reflection:

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Imam 'Ali (as) has said, “Silence is the garden of contemplation.”[94]
The person who speaks too much does not have the time to think, nor does he have time to study and do research. However when one is quiet, new thoughts and views are able to come into his head which get him to start thinking and contemplating on other issues.
Thus, when a person's tongue starts working (and he speaks too much), then there is no opportunity left for him to reflect and ponder. For this reason it has been stated that you should associate yourself with those people who speak less since they will inspire you with wisdom.
This is just a small section on the traditions in relation to silence.
Continuing on, the forty-seventh characteristic of a true believer is that he is truthful in his speech and when one does speak, his words are carefully thought out and truthful. It has been mentioned in the traditions that truthfulness in speech is one sign of true faith and it has been stated, “Do not examine people through the Salat they perform or the fasts that they keep, rather, examine and test them through the truthfulness of their speech. If their tongue is under control, then they have some worth to them and if their tongue is not under their control, then they have no worth to them and even if they perform worship of Allah, this worship has no merit in it.”
For every single Prophet that Allah (SwT) raised up, He commanded them to follow two principles in their mission:

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“Maintain and return trusts given to them and truthfulness in their speech.”
Every morning, the tongue speaks to the other parts of the body and asks how they are doing. The rest of the body parts reply to the tongue that, “If you leave us, then we will all be okay!”
Insha-Allah, all of us will take this issue as something serious and will speak less and think and will also consider whatever we speak to be a part of the actions that we do (that we will have to account for) and we will not take part in those gatherings in which vain and useless talk is going on.
It is our hope that Allah (SwT) gives us all the ability to act according to these commandments.!
Notes:
[89] Bihar al-Anwar, vol. 64, pg. 311
[90] Mizan al-Hikmah, Under the word sumt, tradition 10805
[91] Ibid., tradition 10809
[92] Ibid., tradition 10816
[93] Ibid., tradition 10822
[94] Ibid., tradition 10823