John Calvin Commentary Psalms 9:2

"I will be glad and exult in thee; I will sing praise to thy name, O thou Most High." — Psalms 9:2 (ASV)

I will rejoice and exult in you. Observe how the faithful praise God sincerely and without hypocrisy when they do not rest on themselves for happiness and are not intoxicated with foolish and carnal presumption, but rejoice in God alone; this is nothing else than to seek the substance of their joy from the favor of God, and from no other source, since perfect happiness consists in it.

I will rejoice in you. We ought to consider how great the difference and opposition is between the character of the joy that people endeavor to find in themselves and the character of the joy that they seek in God. David, to express more forcibly how he renounces everything that might captivate or occupy him with vain delight, adds the word exult. By this, he means that he finds in God such a full and overflowing abundance of joy that he does not need to seek even the smallest drop elsewhere.

Moreover, it is important to remember what I have previously observed: David calls to mind the testimonies of divine goodness that he had formerly experienced, in order to encourage himself with greater alacrity to open his heart to God and to present his prayers before Him. One who begins his prayer by affirming that God is the great source and object of his joy fortifies himself beforehand with the strongest confidence in presenting his supplications to the Hearer of prayer.