Many — This verse seems to be interposed as a wall of partition, between that which David speaks in his own person, and that which he speaks in the person of the Messiah, in the following verses.
Related Commentaries of Psalms 40:5
Psalms 40:5
5 Many, O LORD my God, are thy wonderful works which thou hast done, and thy thoughts which are to us-ward: they cannot be reckoned up in order unto thee: if I would declare and speak of them, they are more than can be numbered.