Synopsis of the Books of the Bible, by John Nelson Darby, [1857-62], at sacred-texts.com
The enemy in Psalm 42 is the outward enemy and oppressor the Gentile. Though in circumstances, of course, and not in the depths of atonement, it is interesting to see the analogy in Verse 3 (Psa 43:3) with what the Lord said upon the cross. Psalm 43 is a supplementary psalm to the former: only that here the ungodly nation, the Jews, are before us, and the deceitful and unjust man, the wicked one; though the Gentile oppressor be yet there (Psa 43:2). We know they will both be there in that day. From the Jewish nation being now in the scene, the return to the holy hill and tabernacle and altar of God are more before the mind of the remnant. Verses 3-4 (Psa 43:3-4) form the groundwork of the book.