In verse 13, he speaks somewhat more particularly, addressing the defilement of the tongue, again turning to the psalms for his evidence.  Psalm 5:9 tells us that the throat of the wicked man is an open sepulcher, full of corruption and vileness, and that deceit is in the tongues of men.  Well should we know how much God hates lying, since He forbade it in the 9th of His 10 commandments.  The apostle also borrows from Psalm 140:3 to poetically describe the wicked mouth of the sinner as being like the poison of asps.  How often have we injured others, or been injured by the tongues of others!  The inability of even the best of men to guard his tongue so closely that he never sins with that little instrument is proof of how deeply planted is the corruption of sin in our inmost being.

The 14th verse continues in the same line, borrowing from Psalm 10:7 to describe the mouth of the sinner as being full of cursing and bitterness.  The tongue of man, given to him by God, is often used to curse the very God Who planted it, and even more frequently to curse and revile men who are made in the image of God.  Bitter things are spoken against our Creator, against His providence, and against our fellow creatures.  The ease with which men embrace foul patterns of speech is, once again, powerful evidence of the truth of the apostle’s doctrine of the thorough corruption of man by sin, and his hopelessness before God because of it.