Vs. 1-5 are mostly the same as in Psalm 42.
Because we know that “no prophecy of Scripture is of any private interpretation, for prophecy never came by the will of man, but holy men of God spoke as they were moved by the Holy Spirit” (2 Peter 1:20-21), then it is useless to exhaust oneself with background information that is not clearly connected with a passage of Scripture! Often, expositors seek their own glory, rather than seeking the truth in a Scripture, and overlook the Apostle Peter’s warning: “Therefore, beloved, looking forward to these things, be diligent to be found by Him in peace, without spot and blameless; and consider that the longsuffering of our Lord is salvation–as also our beloved brother Paul, according to the wisdom given to him, has written to you, as also in all his epistles, speaking in them of these things, in which are some things hard to understand, which untaught and unstable people twist to their own destruction, as they do also the rest of the Scriptures. You therefore, beloved, since you know this beforehand, beware lest you also fall from your own steadfastness, being led away with the error of the wicked; but grow in the grace and knowledge of our Lord and Savior Jesus Christ” (2 Peter 3:14-18).
When passages of Scripture seem very similar, then the normal reasoning seems to be that they were written at about the same time (Examples, Ephesians & Colossians; 2 Peter & Jude; Psalm 42 & 43). In fact, some commentators unnecessarily make Psalm 43 an extension of Psalm 42! Though Jesus Christ preached His “Sermon on the Mount,” as we call it, He could preach various parts of it on other occasions. If the Holy Spirit can inspire the teaching on one occasion, He can do the same another time! So with Psalm 43, it could have been similarly inspired by the Holy Spirit at another time than that which prompted Psalm 42.
Verse 1: The writer seeks relief from “an ungodly nation,” “the deceitful and unjust man,” and “the oppression of the enemy” by God sending “light” and “truth” that would lead back to correct worship of God (“Your holy hill,” “Your tabernacle,” “the altar of God”). It sounds similar to Jesus’ statement to the Samaritan woman: “”But the hour is coming, and now is, when the true worshipers will worship the Father in spirit and truth; for the Father is seeking such to worship Him” (John 4:23). Corruption in, or absenteeism from, spiritually-correct worship of God is the Devil’s method of weakening Christians. Paul warns Christians, because of their corrupted practice of the Lord’s Supper, “many are weak and sick among you, and many sleep” (1 Corinthians 11:30).
Verse 2: echoes Psalm 42:9.
Verses 3-4: speak of the worshipper’s missing the joy of worshiping God, and it is similar to Psalm 42:1-4.
Verse 5: is the same as Psalm 42:11, and almost the same as Psalm 42:5.
All Scriptures and comments are based upon the New King James Version, unless otherwise noted.