What does Psalm 7:3 mean?

Scripture does not explicitly identify any sin, by David, that would match what he says in these verses. This seems to be David's response to an accusation, more than an actual confession. In prior verses, David mentioned his enemies (Psalm 7:1–2), so these verses (Psalm 7:4–5) may be a declaration of his innocence. Less likely is that they are a sincere plea for God's mercy if their accusations turn out to be true.

This verse uses two "if" statements: "if I have done this," and "if there is wrong in my hands." That does not mean David wonders whether he has committed these acts. Rather, David's enemies may have slandered him. They might have accused him of taking bribes or committing some treachery. Since David's conscience was clear and his motives and deeds were pure, he asked the Lord to search him and vindicate him. This is somewhat like a modern person saying, "you can take me to jail if I'm lying, but I know I'm telling the truth."

Believers may be slandered, but they should live in such a way that no one can legitimately bring an accusation against them. Paul insists in 1 Timothy 3 that an overseer must be above reproach and be well-thought of by outsiders (1 Timothy 3:2, 7), and he writes that all believers ought to be "blameless and innocent, children of God without blemish" (Philippians 2:15). Peter expresses a similar idea in his writing (1 Peter 3:13–17).