10 My shield is with God,
who saves the upright in heart.
11 God is a righteous judge,
and a God who feels indignation every day.
12 If a man does not repent, God will whet his sword;
he has bent and readied his bow;
13 he has prepared for him his deadly weapons,
making his arrows fiery shafts.
14 Behold, the wicked man conceives evil
and is pregnant with mischief
and gives birth to lies.
15 He makes a pit, digging it out,
and falls into the hole that he has made.
16 His mischief returns upon his own head,
and on his own skull his violence descends.
17 I will give to the Lord the thanks due to his righteousness,
and I will sing praise to the name of the Lord, the Most High.
Yet again the psalmist refers to God as his shield (Psa 3:3; 5:12). Again the covenant nature of this description is highly likely (Gen 15:1). Again this “defense” (KJV) is the righteousness of God as judge who will not relent against those who will not repent (v. 12-13). The war images of God’s judgment bring to mind the vision of John against Jerusalem in A.D. 70 (Rev 6:2, 4).
The judgment upon evil men is the very evil they conceive. There is nothing brought down that is not wrought from their own actions. We receive wages for our sins (Rom 6:23). What we reap we shall sow (Gal 6:7-8). Judgment for our sin is the righteous payment of what we have earned.
Knowing all this the psalmist reflects back on God, his covenant shield, and His righteousness. For it preserves God’s people.