Blessed be Jehovah, my strength. It is very evident that David, since he celebrates the favor of God in such high terms, had not only obtained the kingdom, but gained signal victories. When he calls God his strength, he acknowledges that any courage he had was given him from above, not only because he had been made from a country shepherd a mighty warrior, but because the constancy and perseverance he had shown was signally a gift from God. This term answers better than were we to translate it rock; for, by way of explanation, he adds immediately afterwards, that he had been formed under God's teaching for war. The words certainly imply an acknowledgment, that though of a warlike spirit, he was not born for warlike enterprises but needed to undergo a change. What kind of a commencement, for example, did he show in the case of Goliah? That attempt would have been preposterous on any other supposition than his being upheld by secret divine support, so as to be independent of mere human help. (1 Samuel 17:40.)

Blessed be the Lord my strength - Margin, as in Hebrew, "my rock." See the notes at Psalm 18:46, where the same expression occurs in the Hebrew.
Which teacheth my hands to war - Hebrew, "To the war." See the notes at Psalm 18:34. The Hebrew is not precisely alike, but the sense is the same.
And my fingers to fight - Hebrew, my fingers to the fight. That is, he teaches my fingers so that I can skillfully use them in battle. Probably the immediate reference here is to the use of the bow - placing the arrow, and drawing the string.

Teacheth my hands to war - To use sword, battle-axe, or spear.
And my fingers to fight - To use the bow and arrows, and the sling.

"[A Psalm] of David." Blessed [be] the LORD my strength, which (a) teacheth my hands to war, [and] my fingers to fight:
(a) Who out of a poor shepherd has made a valiant warrior and mighty conqueror.

Blessed be the Lord my strength,.... The author and giver of his natural strength of body, and of the fortitude of his mind, and of all the spiritual strength he had, to exercise grace, to bear up under afflictions and trials, to perform duty, and withstand enemies. It may be applied to Christ, the antitype of David, the man of God's right hand, he has made strong for himself. It may be rendered, "my rock" (c); to whom the psalmist fled for shelter, when in distress and overwhelmed; and on whom he built his faith, and hope of eternal salvation, as well as depended on him for all supplies of grace and strength, and for help and succour in all times of need. The Septuagint, Vulgate Latin, Ethiopic, and Arabic versions, render it, "my God": and so the word "rock" is used for God, Deuteronomy 32:30;
which teacheth my hands to war, and my fingers to fight; he took him from being a shepherd, and made him a soldier; and from being the leader of a flock of sheep, to be a general of armies; and all his military skill in marshalling of troops, in leading them on to battle, and bringing them off as well as all his courage and success, were from the Lord: he whose hands and fingers had been used to the shepherd's crook, and to the handling of the harp and lyre, were taught how to handle the sword, the bow, the shield, and spear. God is a man of war himself; and he teaches the art of war, as he does husbandry and other things; see Exodus 15:3; and so the Lord furnishes his people, who are here in a militant state, with spiritual armour, to fight against their spiritual enemies; he teaches them how to put it on, and directs them how to make use of every piece of it; as well as gives them boldness to face their enemies, and victory over them.
(c) "rupes mea", Montanus, Tigurine version, Junius & Tremellius, Piscator, &c. so Ainsworth.

When men become eminent for things as to which they have had few advantages, they should be more deeply sensible that God has been their Teacher. Happy those to whom the Lord gives that noblest victory, conquest and dominion over their own spirits. A prayer for further mercy is fitly begun with a thanksgiving for former mercy. There was a special power of God, inclining the people of Israel to be subject to David; it was typical of the bringing souls into subjection to the Lord Jesus. Man's days have little substance, considering how many thoughts and cares of a never-dying soul are employed about a poor dying body. Man's life is as a shadow that passes away. In their highest earthly exaltation, believers will recollect how mean, sinful, and vile they are in themselves; thus they will be preserved from self-importance and presumption. God's time to help his people is, when they are sinking, and all other helps fail.

The whole of this first strophe is an imitation of David's great song of thanksgiving, Ps 18. Hence the calling of Jahve "my rock," Psalm 18:3, Psalm 18:47; hence the heaping up of other appellations in Psalm 144:2, in which Psalm 18:3 is echoed; but וּמפלּטי־לי (with Lamed deprived of the Dagesh) follows the model of 2-Samuel 22:2. The naming of Jahve with חסדּי is a bold abbreviation of אלהי חסדּי in Psalm 59:11, 18, as also in Jonah 2:8 the God whom the idolatrous ones forsake is called הסדּם. Instead of מלחמה the Davidic Psalm also poetically say קרב, Psalm 55:22, cf. Psalm 78:9. The expression "who traineth my hands for the fight" we have already read in Psalm 18:35. The last words of the strophe, too, are after Psalm 18:48; but instead of ויּדבּר this poet says הרודד, from רדד = רדה (cf. Isaiah 45:1; Isaiah 41:2), perhaps under the influence of uwmoriyd in 2-Samuel 22:48. In Psalm 18:48 we however read עמּים, and the Masora has enumerated Psalm 144:2, together with 2-Samuel 22:44; Lamentations 3:14, as the three passages in which it is written עמי, whilst one expects עמים (ג דסבירין עמים), as the Targum, Syriac, and Jerome (yet not the lxx) in fact render it. But neither from the language of the books nor from the popular dialect can it be reasonably expected that they would say עמּי for עמּים in such an ambiguous connection. Either, therefore, we have to read עמים,
(Note: Rashi is acquainted with an otherwise unknown note of the Masora: תחתיו קרי; but this Ker is imaginary.)
or we must fall in with the strong expression, and this is possible: there is, indeed, no necessity for the subduing to be intended of the use of despotic power, it can also be intended to God-given power, and of subjugating authority. David, the anointed one, but not having as yet ascended the throne, here gives expression to the hope that Jahve will grant him deeds of victory which will compel Israel to submit to him, whether willingly or reluctantly.