What does Psalm 37:39 mean?

David testifies that God saves the righteous and acts as their refuge in time of trouble. David learned firsthand that God is more than able to rescue His people in times of trouble. No enemy that sought to kill David succeeded, despite great odds. The Lord always protected him.

For example, both when David was threatened by the giant Goliath (1 Samuel 17:41–51) and a fugitive in the wilderness (1 Samuel 23:14), the Lord protected him. The Lord also delivers the righteous—those who trust in the Savior—from eternal judgment (John 10:28). Romans 6:23 explains that God's gift is eternal life in Christ Jesus.

When the flood waters claimed the lives of all who breathed in the time of Noah, Noah and his family were safe in the ark. The Lord had shut them in (Genesis 7:16; 2 Peter 2:5). Similarly, the righteous are safe in Christ. He is our ark! Also, when trials engulf us, we need not fret but trust, knowing God cares for us (1 Peter 5:7).