“The Lord is my rock and my fortress and my deliverer, my God, my rock, in whom I take refuge, my shield, and the horn of my salvation, my stronghold.” -Psalm 18:2
In verse one, David declared his love for the one who is his strength. In verse two, he expounds on the quality of the Lord’s strength. The Lord is David’s rock. The Hebrew word translated “rock” is literally a crag or high cliff. Specifically, the Lord is his fortress, מְצוּדָה (M’sad). Finally, The Lord is his deliverer (place of escape). In typical poetic fashion, David expounds further for emphasis. (One of poetry’s great strengths is that fact that it is superfluous and exaggerated). The Lord is David’s M’sad, his shield, the very strength of his salvation, his stronghold.
Perhaps, the story of the Roman siege of Masada (Heb., Rocky Mountain fortress) comes to mind. The Jewish historian, Josephus, tells of the mass suicide of the Sicarii rebels and resident Jewish families of the Masada fortress in one of the final events in the First Jewish–Roman War, occurring from 73 to 74 CE. After being besieged by the Roman army for several months while the Romans moved thousands of tons of earth and stone to build a wall and bridge that finally allowed them to access the mountain fortress because the Jewish residents did not counterattack their besiegers. This kind of mountain fortress is what David has in mind. This is what the Lord is to him in the face of his enemies. The only difference is the Lord actually fights our battles for us, as the Psalmist notes later in the Psalm.