Psalms 43:4

Then will I go unto the altar of God,.... Which was in the tabernacle, either of burnt offerings, or of incense, there to offer up the sacrifice of praise and thanksgiving for mercies received. The altar under the Gospel dispensation is Christ, on which such sacrifices being offered, are acceptable to God, Hebrews 13:10;

unto God my exceeding joy; as over the mercy seat, upon a throne of grace, and as his covenant God; or this is exegetical of the altar, which is Christ, God over all, blessed for ever; and who is the object of the unspeakable joy of his people, in his person, righteousness, and salvation;

yea, upon the harp will I praise thee, O God, my God: the harp is a musical instrument, used in that part of public worship which concerned the praise of God under the former dispensation, and was typical of that spiritual melody made in the hearts of God's people when they sing his praise, see Revelation 5:8.