NASB
Note: Some scholars suggest that Psalms 42 and 43 are likely a single poem. Psalm 43 has no title, which is seen as a reason for putting the two psalms together. The language of the psalm indicates that the psalmist was in some kind of trouble or facing a threat.
43:1 Vindicate me [undertake my cause], O God, and plead my case against an ungodly [unmerciful, cruel] nation [possibly a reference to a large company of enemies];
O deliver me [that the world may know of my innocence] from the deceitful and unjust [deceit and injustice are companions] man [context seems to point to the time of Absalom’s rebellion (2 Sam. 15)]!
43:2 For Thou art the God of my strength [cf. Ps. 18:1-2]; why hast Thou rejected [to cast off; cf. Ps. 22:1] me [the cry of one who “feels” alone and vulnerable; cf. Ps. 42:9; because the Islamist was under intense pressure, he wrongly concluded that he had been cast off or was rejected by God]?
Why do I go mourning [cf. Ps. 42:9] because of the oppression of the enemy?
43:3 O send out Thy [God’s] light [the plea of those who find themselves in oppressive darkness; a plea for God’s favor] and Thy truth [the plea of those who are surrounded by deceitful people], let them [the light and truth of God’s word] lead me [God’s light and truth are reliable guides];
Let them bring me [in a time of trouble the psalmist longed to return to the familiar places where he enjoyed the presence of God] to Thy holy hill [God’s light and truth will lead one toward the presence and the heart of God],
And to Thy dwelling places [God’s light and truth will lead one to the place where God (and therefore safety) dwells].
43:4 Then I will go to the altar [the place where both sacrifices and thanksgiving were offered] of God [the place where things become clearer; read Ps. 73:16-17],
To God my exceeding joy [God was the One who made the psalmist joyous];
And upon the lyre [a musical instrument used in the worship of God] I shall praise Thee, O God, my God.

43:5 [cf. Ps. 42:5,11] Why are you in despair [to be cast down, to be depressed, to sink under the weight of sorrow], O my soul?
And why are you disturbed within me [suggests an agitated and troubled mind]?
Hope in God [the psalmist commanded himself to remember that God would deliver him from all his troubles], for I shall again [because God would indeed vindicate and deliver him] praise Him,
The help of my countenance [our countenance changes when God is present; He is the One who “lifts my head” (Ps. 3:3)], and my God.