{a} The LORD is my rock, and my fortress, and my deliverer; my God, my strength, in whom I will trust; my buckler, and the horn of my salvation, and my high tower.

(a) He uses this diversity of names to show that as the wicked have many means to hurt, so God has many ways to help.

Wesley's Notes

18:2 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.

King James Translators' Notes

my strength: Heb. my rock

Jamieson-Fausset-Brown Bible Commentary

2, 3. The various terms used describe God as an object of the most implicit and reliable trust.

rock-literally, "a cleft rock," for concealment.

strength-a firm, immovable rock.

horn of my salvation-The horn, as the means of attack or defense of some of the strongest animals, is a frequent emblem of power or strength efficiently exercised (compare De 33:17; Lu 1:69).

tower-literally, "high place," beyond reach of danger.

Matthew Henry's Concise Commentary

18:1-19 The first words, I will love thee, O Lord, my strength, are the scope and contents of the psalm. Those that truly love God, may triumph in him as their Rock and Refuge, and may with confidence call upon him. It is good for us to observe all the circumstances of a mercy which magnify the power of God and his goodness to us in it. David was a praying man, and God was found a prayer-hearing God. If we pray as he did, we shall speed as he did. God's manifestation of his presence is very fully described, ver. 7-15. Little appeared of man, but much of God, in these deliverances. It is not possible to apply to the history of the son of Jesse those awful, majestic, and stupendous words which are used through this description of the Divine manifestation. Every part of so solemn a scene of terrors tells us, a greater than David is here. God will not only deliver his people out of their troubles in due time, but he will bear them up under their troubles in the mean time. Can we meditate on ver. 18, without directing one thought to Gethsemane and Calvary? Can we forget that it was in the hour of Christ's deepest calamity, when Judas betrayed, when his friends forsook, when the multitude derided him, and the smiles of his Father's love were withheld, that the powers of darkness prevented him? The sorrows of death surrounded him, in his distress he prayed, Heb 5:7. God made the earth to shake and tremble, and the rocks to cleave, and brought him out, in his resurrection, because he delighted in him and in his undertaking.