What does Psalm 26:9 mean?

In this psalm, David is declaring his sincere devotion to God. As part of that, he lived with an intentional separation from those who were openly wicked (Psalm 26:4–5). Instead, he took joy in worshipping the Lord and spending time in praise and celebration (Psalm 26:6–8). A theme of this psalm is David's plea for vindication (Psalm 26:1)—to be cleared of wrongdoing and spared from consequences that he has not earned.

Statements such as this echo the wisdom of Proverbs 13:20. Those who participate in evil can expect negative earthly consequences. Those who associate with evil people risk being caught up in those results. Even so, suffering in this life is a lesser concern, compared to eternity.

David understood that hypocrites—sinners and bloodthirsty men—mingled with sincere worshipers. He also understood the Lord would sweep them away in judgment. Jesus spoke about the mingling of the lost with the saved. He referred to wheat versus weeds and sheep versus goats (Matthew 13:24–30; 25:31–46). Ultimately, the "weeds" and "goats" will perish.

Believers must be vigilant so they will not be like hypocrites. First Corinthians 10:12 cautions: "Let anyone who thinks that he stands take heed lest he fall." Although it may be difficult at times to distinguish between believers and unbelievers, the Lord knows who belongs to Him and who doesn't. Second Timothy 2:19 carries this assurance and provides a command: "But God's firm foundation stands, bearing this seal: 'The Lord knows those who are his,' and, 'Let everyone who names the name of the Lord depart from iniquity.'"