Proverbs 10:20

We are here taught how to value men, not by their wealth and preferment in the world, but by their virtue. I. Good men are good for something. Though they may be poor and low in the world, and may not have power and riches to do good with, yet, as long as they have a mouth to speak, that will make them valuable and useful, and upon that account we must honour those that fear the Lord, because out of the good treasure of their heart they bring forth good things. 1. This makes them valuable: The tongue of the just is as choice silver; they are sincere, freed from the dross of guile and evil design. God's words are compared to silver purified (Psa 12:6), for they may be relied on; and such are the words of just men. They are of weight and worth, and will enrich those that hear them with wisdom, which is better than choice silver. 2. It makes them useful: The lips of the righteous feed many; for they are full of the word of God, which is the bread of life, and that sound doctrine wherewith souls are nourished up. Pious discourse is spiritual food to the needy, to the hungry. II. Bad men are good for nothing. 1. One can get no good by them: The heart of the wicked is little worth, and therefore that which comes out of the abundance of his heart cannot be worth much.

— Matthew Henry's Concise Commentary (public domain)

Right speech is the fruit of a good heart, but the wicked show theirs to be useless.

— Jamieson-Fausset-Brown Commentary (public domain)