Charles Ellicott Commentary Psalms 43:4

"Then will I go unto the altar of God, Unto God my exceeding joy; And upon the harp will I praise thee, O God, my God." — Psalms 43:4 (ASV)

God my God. —An expression used in this collection instead of the more usual “Jehovah my God.” (Compare Psalm 45:7, and for its import see General Introduction, and Psalm 50:7, Note.)