For who is God, save the Lord? and who is a rock, save our God? See Gill on Psalm 18:31.

32 For who is God save Jehovah,
And who a rock save our God?
33 This God is my strong fortress,
And leads the innocent his way.
34 He makes my feet like the hinds,
And setteth me upon my high places;
35 He teacheth my hands to fight,
And my arms span brazen bows.
There is no true God who can help, except or by the side of Jehovah (cf. Deuteronomy 32:31; 1-Samuel 2:2). צוּר, as in 2-Samuel 22:2. This God is "my strong fortress:" for this figure, comp. Psalm 31:5 and Psalm 27:1. חיל, strength, might, is construed with מעוּזי, by free subordination: "my fortress, a strong one," like עז מחסי (Psalm 71:7; cf. Ewald, 291, b.). יתּר for יתר, from תּוּר (vid., Ges. 72; Olshausen, Gram. p. 579), in the sense of leading or taking round, as in Proverbs 12:26. God leads the innocent his way, i.e., He is his leader and guide therein. The Keri דּרכּי rests upon a misunderstanding. There is an important difference in the reading of this verse in Ps 18, viz., "The God who girdeth me with strength, and makes my way innocent." The last clause is certainly an alteration which simplifies the meaning, and so is also the first clause, the thought of which occurs again, word for word, in 2-Samuel 22:40, with the addition of למּלחמה. איּלה or איּלת, the hind, or female stag, is a figure of speech denoting swiftness in running. "Like the hinds:" a condensed simile for "like the hinds' feet," such as we frequently meet with in Hebrew (vid., Ges. 144, Anm.). The reference is to swiftness in pursuit of the foe (vid., 2-Samuel 2:18; 1-Chronicles 12:8). רגליו, his feet, for רגלי (my feet) in the psalm, may be accounted for from the fact, that David had spoken of himself in the third person as the innocent one. "My high places" were not the high places of the enemy, that became his by virtue of conquest, but the high places of his own land, which he maintained triumphantly, so that he ruled the land for them. The expression is formed after Deuteronomy 32:13, and is imitated in Habakkuk 3:19. למּד is generally construed with a double accusative: here it is written with an accusative and ל, and signifies to instruct for the war. נחת, in the psalm נחתה, on account of the feminine זרועתי, is not the Niphal of חתת, to be broken in pieces, but the Piel of נחת, to cause to go down, to press down the bow, i.e., to set it. The bow of brass is mentioned as being the strongest: setting such a bow would be a sign of great heroic strength. The two verses (2-Samuel 22:34 and 2-Samuel 22:35) are simply a particularizing description of the power and might with which the Lord had endowed David to enable him to conquer all his foes.