What does Psalm 54:5 mean?

Though David was betrayed by the people of Ziph and pursued by Saul (1 Samuel 23:19–20), he was confident that God would rescue him. His prayer for rescue (Psalm 54:1–3) was followed by statements of David's assurance (Psalm 54:4).

Here, David sets aside the burden of revenge. David believes those who seek to kill him we be repaid by God. This is an extension of the Lord's faithful promises and holy nature. These are not idle words, either. On at least two occasions, David had an opportunity to kill Saul, but refused to attack God's then-anointed king of Israel (1 Samuel 24:4–8; 26:8–17). Not only did David state that revenge is best left for God, but he also lived out that belief in his situations.

Instead of retaliating against enemies for the harm they inflict, believers are told not to avenge themselves, "but leave it to the wrath of God, for it is written, 'Vengeance is mine, I will repay, says the Lord'" (Romans 12:19). Proverbs 26:27 emphasizes the fact that revenge attempts often backfire, saying, "Whoever digs a pit will fall into it, and a stone will come back on him who starts it rolling." In many cases, the person who plans evil brings damage to themselves; with God's guidance, there is no reason for a believer to seek revenge (Proverbs 20:22; 24:29).