Proverbs 10:20

The tongue of the just [is as] choice silver
Which utters things precious, pure, pleasant, and profitable; things for worth and value as choice silver; the doctrines of the Gospel, the power of which he has felt upon his heart; the precious promises of it, which have been applied unto him; and the rich experience of grace he has been favoured with: things pure and incorrupt, like silver free from dross; as the doctrines of grace, fetched out of the mines of the sacred Scripture, free from the dross of error, without any human mixture; consistent and all of a piece, and which tend to purity of heart and life; things the reverse of a corrupt communication, nothing filthy and unclean; a pure language, the language of Canaan; the language of repentance, faith, and love, of prayer and thankfulness: things which are grateful and acceptable, are with grace, and minister grace to the hearers; things profitable and edifying; for the righteous man's mouth speaks wisdom, and his tongue talks of judgment; and his lips feed many, as in ( Proverbs 10:21 ) ; see ( Psalms 37:30 ) ; the heart of the wicked [is] little worth;
good for nothing, as the Vulgate Latin version. The righteous man's tongue is better than the wicked man's heart; there is no good thing in his heart naturally; all manner of evil is in it, and comes out of it; no sin can be named but what is in his heart; all that is in it is sinful; the thoughts of it, and the imagination of his thoughts, are only evil, and that continually; the affections are inordinate, and set on sinful lusts and pleasures; the mind and conscience are defiled with sin; the understanding is darkened with it, and the will is obstinate and perverse, and bent upon it: his heart is wicked, and exceedingly wicked; it is wickedness itself, very wickedness, desperately wicked, incurably so without the grace of God. Such therefore know not their hearts who say they have good hearts; and they are fools that trust in them: this shows the necessity of regeneration, and that powerful and efficacious grace is requisite to it.