What does Psalm 31:23 mean?

After explaining his approach to trust in God (Psalm 31:19–22), David turns his attention to the believers in Israel. He exhorts them to love the Lord. This exhortation echoes the first and greatest commandment the Lord gave the people of Israel. He announced: "You shall love the LORD your God with all your heart and with all your soul and with all your might" (Deuteronomy 6:5). Jesus said, "This is the great and first commandment" (Matthew 22:38). David assures the faithful that God preserves them. In other words, He protects and keeps them. He gives them grace to endure every affliction (2 Corinthians 12:9), and He escorts them safely to heaven (John 10:28).

On the other hand, God serves justice to proud evildoers, in abundance. A famous illustration of this is Jesus' story about a beggar named Lazarus, who was transported to Paradise, as opposed to an unrighteous rich man, who died and suffered in hell (Luke 16:19–23). Unbelievers may prosper in this life, but they will experience the same judgment as anyone else after they die (Hebrews 9:27).