One of the topics that the book of Proverbs touches on a great deal is that of our tongues and the benefit or damage that they can do. Here we have another of those proverbs that counsel us on having a tongue that honors and glorifies God.
The mouth of the righteous is described here liks a fruitful tree. The word "flows" is the Hebrew word "nub" which speaks of something that flourishes. It means to bring forth or to bear fruit. It is also used in the Old Testament to speak of someone who is experiencing prosperity. We are told that the mouth of the righteous has an abundant harvest of wisdom. The words that the righteous man speaks are like a tree laden with fruit. That fruit when eaten will lead us to wise, godly choices. The reason this is true is because men speak out of their mouths what resides in their hearts. The righteous man can speak forth wisdom because the Word of God dwells in his heart. Therefore as his heart gives his lips the substance of his words - those words will be in accordance with the Word of God. Truly then, you will get wisdom from the things that he says.
Not only is the mouth of the godly man mentioned in this proverb, but also the perverted tongue as well. Perverse as used here means something deviated and distorted. It describes deceptive and corrupt speech. Here in Proverbs it refers to one who intentionally distorts what is straight and right. Thus, this man is not sharing God's wisdom, but a perversion of it. This kind of tongue will be cut out. This may sound gruesome at first, but the idea is that of cutting something out of the ground. It referred to uprooting a plant that was not productive - or one that was counter productive. The picture that we have from this proverb is an agricultural one. We have a mouth that is like a fruitful tree - and a tongue that is like a harmful weed. One is a blessing, the other is a curse. One will be welcomed as wisdom flows forth from it, while the other will be viewed as a weed that disrupts the production of a garden. The difference between these two is very simple. One comes from a man who loves with is right in the eyes of the Lord, while the other comes from a man who distorts what is right and true. He does so because he values having his own desires fulfilled, rather than doing what is right and good for all those around him.