Psalm 7:4 is a strong statement of innocence and a curse upon himself if he is guilty of wrongdoing. Let's break it down:

"If I have rewarded evil to him who was at peace with me..." This is the first part of a conditional curse. David is saying, "If I have repaid someone who was peaceful and friendly towards me with evil..." In other words, if he betrayed someone who trusted him.

"(yes, I have delivered him who without cause was my adversary)..." This is a parenthetical statement emphasizing the opposite of the first clause. It strengthens his claim of innocence. It means, "In fact, I have even saved or protected someone who was my enemy for no good reason, without any justification for their animosity."

In essence, the verse is David declaring that he has not betrayed a friend, and has actually shown kindness even to his enemies. He is setting up a powerful contrast to demonstrate his integrity.

The verse suggests that David believes himself to be falsely accused. He's so confident in his innocence that he's willing to invoke a curse upon himself if the accusations are true.

Here's how to interpret the verse's implication in the broader context of the psalm:

Declaration of Innocence: It's a key part of David's plea to God for justice. He's asserting his innocence against his accusers (likely those mentioned in verse 1).
Moral High Ground: David is portraying himself as a virtuous person who treats others well, even those who are hostile towards him.
Seeking Divine Justice: By making this declaration, David is essentially inviting God to judge the situation. He believes that because he has acted justly, God will vindicate him.
Conditional Curse: The curse underscores the seriousness of the situation and David's confidence in his innocence. He is willing to suffer if he has done what he is accused of.

The verse highlights David's character as a righteous person who values loyalty, peace, and even kindness to enemies, and uses this assertion as a basis for his appeal to God for justice.