What does Psalm 39:7 mean?

Seen from an eternal perspective, life is brief. Pursuing wealth and shallow bickering is a waste of what little time we have (Psalm 39:4–6). David eased his frustration by asking God to remind him of life's brevity (Psalm 39:1–4). Remembering that God is much greater than our struggles can ease angst over difficult circumstances. In this verse, David makes that connection by pointing to God as his only and ultimate hope.

The best things in life are not things—objects or money—but the occasions in which a person glorifies the Lord. David understood that quantity of years is not as important as the quality of one's life. How many moments a person has is not as important as what one does with those moments (Matthew 6:19–20). So, David weighed what pleases the Lord and the rewards which follow. He then chose to "wait on the Lord:" meaning to trust and hope in Him alone.

It's possible some of David's current struggle was the result of his own sin (Psalm 39:8–11). Therefore, he turned from his sin and looked to the Lord for restored fellowship. Surely the Lord does not want His people to engage in self-pity over their sins. He wants them to look to Him, hope in Him, confess their sins, and serve Him (Philippians 3:13–14; Hebrews 10:19–25; 12:3–13; 1 John 1:8—2:6). Romans 12:12 exhorts believers to "rejoice in hope, be patient in tribulation, be constant in prayer."