Rock — To which I flee for refuge, as the Israelites did to their rocks. Horn — It is a metaphor from those beasts whose strength lies in their horns.
Related Commentaries of Psalms 18:2
Psalms 18:2
2 The LORD is my rock, and my fortress, and my deliverer; my God, my strength,a in whom I will trust; my buckler, and the horn of my salvation, and my high tower.