What does Psalm 31:20 mean?

Over his lifetime, David was threatened by many enemies (1 Samuel 17:44–45; 19:2; 2 Samuel 15:14). In this psalm, he has reflected on God's repeated rescue (Psalm 31:3–5). That leads him to praise the Lord for acting as a safe place in which David can trust. The imagery is of God acting as a cover, or even as a room where David and other righteous people would be safe from harm. One possible inspiration for this was the Holy of Holies, a sacred room in the tabernacle where God's presence dwelled (Exodus 26:32–34). There, in the Lord's presence, David felt free from the violent language his enemies used against him (Psalm 31:11–14).

God's physical presence is often used as a symbol for His protection. Some Old Testament miracles use dramatic rescue from physical danger to encourage faith in God. Undoubtedly, the Lord was present in the fiery furnace that left Daniel's three friends unharmed (Daniel 3:24–27). The fire merely burned off the ropes that bound them. When their persecutor, King Nebuchadnezzar, peered into the furnace, he cried out that he saw a fourth person in the fire, who appeared to be divine (Daniel 3:25). Likewise, Daniel was safe in the pit filled with hungry lions, because the Lord kept him safe. Daniel declared to the king: "My God sent his angel and shut the lions' mouths, and they have not harmed me" (Daniel 6:22). The safest place for a believer is the Lord's presence.