What does Psalm 31:3 mean?

Along with the first two verses (Psalm 31:1–2), a very similar statement is made in Psalm 71:1–3. David's trust in God was strong. He refers to his Lord as "a rock of refuge" and "a strong fortress" (Psalm 31:2).

"Rock," from the Hebrew root word tsuwr, implies something like a massive boulder, or "rock" as a substance, rather than as a single stone. This imagery, used in the prior verse (Psalm 31:2), suggests strength and stability, perhaps as one might picture a boulder or a mountainside. In blessing Joseph, Jacob called God, "the Stone of Israel" (Genesis 49:24). Moses, too, referred to God as "the Rock" (Deuteronomy 32:4, 15, 18). The term used in this verse is cela', which leverages the idea of security and strength, as in a large cliff face.

"Stronghold" and "fortress" are both translated from the same Hebrew root word. One can imagine a castle-like structure with thick stone walls. The main purpose of that structure is safety and stability, despite being attacked by an enemy.

And yet, David looks to God for more than strength and protection. He also asks God to lead and guide him. Acting for God's "name's sake" means doing what furthers the Lord's will. David wasn't simply praising God for protection, but also for the Lord's holy guidance in his life. In the next verse, David continues blending literal military concepts with spiritual ideas by speaking of how this divine guidance keeps him away from enemy ambush (Psalm 31:4).