This psalm is more like a prayer attempting to invoke God to curse, judge and punish our enemy. This thought in prayer is usually based on a covenant, not just our own human desire for vengeance or justice, see Genesis 12:3 & Deuteronomy 28:1-2 & 15. When David wrote this Psalm by inspiration, he wrote it as a king, being responsible for the welfare and protection of God’s children. David was also responsible for the justice system, the prosecution and execution of capital crimes. This kind of prayer is truly personal, but coming from a King, also has a public aspect towards matters of injustice to the throne of God, not acts of vengeance. David always recognized the truth of Romans 12:19, “Never take your own revenge, beloved, but leave room for the wrath of God, for it is written, ‘VENGEANCE IS MINE, I WILL REPAY,’ says the Lord.” See Deuteronomy 32:35. It is our prerogative to pray for God to avenge wrongs, because vengeance belongs to Him (Deut 32:35; Romans 12:19–21). These prayers are a divinely appointed source of power for believers in their powerlessness. In the face of sustained injustice, hardened enmity, and gross oppression, they are the Christians’ hope that divine justice will indeed be realized—not only in the long term future (2 Thess. 1:6– 10) but also in “the land of the living” (Ps. 27:13). This psalm is not contrary to the New Testament teaching to love and forgive our enemies, see Luke 18:7–8. Forgiveness is often prayed for, but it is never realized without repentance and if our enemy will not repent and seems bent on evil, then they will indeed perish!
v. 8 “Let another take his office.” This statement is understood by Luke as divinely inspired prophecy in the promised Messiah’s establishment of justice, see Acts 1:20 which cites this statement from Psalm 109 as fulfilled with the death of Judas and the appointment of Matthias to the vacated apostleship. Just as David prayed that his chief enemy might be removed from his position of authority, so also Judas, the enemy of David’s greater Son – Jesus Christ, must have Judas removed from his position.
v14, sounds inappropriate from a Christians perspective but “Fathers” have a certain specific responsibility for the sin of their children. The sweetness of vengeance lay in its completeness. The curse must strike backwards as well as forwards, and the root as well as the branch should be destroyed. Undoubtedly the Mosaic Law, Ex. 20:5, which proclaimed that the “iniquity of the fathers should be visited on the children,” suggested this form of punishment. The fact of the matter is that children and children’s children often suffer from the errors, the crimes of their parents, as in the case of alcoholism, drug addiction and even murder (compare Romans 5:12) and the prayer here is, that this regular effect of sin might follow in this instance; that these consequences might not be stopped by divine intervention.
v20 is most likely an appeal to the Mosaic law regarding false witnesses (Deut 19:15–21).
v23, David was not experiencing God’s blessings while writing this Psalm. This made other people question God’s justice and faithfulness. If God would again bless David and curse his enemy, this would show onlookers that God’s promises are trustworthy. In these verses, David described how he felt in his downtrodden condition. “The locust or grasshopper is proverbial as being a defenseless inoffensive little creature that is soon driven away, Job 39:40
v25, Shaking the head can signify rejection or astonishment (Psalm 64:8: Lam. 2:15). The Lord Jesus’ enemies spoke these very words as He hung on the cross (Matt. 27:42-43).
A Christians lesson from this Psalm is this: When attacked, be a prayer first responder. When tempted to sin, look to God and consider the impact upon your family. Be characterized by prayer and praise Christ, regardless of your circumstances. God is faithful!