"A fool also is full of words: a man cannot tell what shall be; and what shall be after him, who can tell him?" (Ecc. 10:14)
I had already written about the importance of being swift to hear. The opposite, speaking too much can be a great problem, and is a characteristic of a fool. Such words will swallow up the fool, pouring out more and more foolishness for all to hear (Ecc. 10:12; Prov. 15:2).
His voice will be known by his multitude of words, and it is highly possible they will not be heeded, even if they have elements of truth of them (Ecc. 5:3). Even if such words are cried out by those in authority, they will not be heard by fools (Ecc. 9:17). Does not even the wisdom of the world say that it is better to be silent than to speak and be known as a fool? See this quote from one of our presidents, here.
So many words can increase one’s chance of saying rash things about the future as well. Things that may or may not happen, forgetting to consider whether or not such things are part of God’s will (Jam. 4:13-14). Not only this, but also such behavior increases one’s chances of sinning as well, which is a great terror (Prov. 10:19).