John Calvin Commentary Psalms 89:20

"I have found David my servant; With my holy oil have I anointed him:" — Psalms 89:20 (ASV)

I have found David my servant. The prophet confirms the same proposition: that there was nothing of royalty in David, who owed everything to God's sovereignty in anticipating him with His grace. This is the meaning of the word found, as if God had said, "When I took him to elevate him, this proceeded entirely from My free goodness."

The name servant, therefore, does not indicate any merit, but refers to the divine call. It is as if God had said that He confirmed and ratified by His authority the sovereign power of David; and if He approved it, its legitimacy is placed beyond all doubt.

The second clause of the verse provides an additional confirmation of God's free election: With my holy oil have I anointed him. This anointing, which was not the fruit of David’s own strategy, but which he obtained contrary to all expectation, was the cause of his elevation to the royal estate.

God, then, having of His own accord and according to His mere good pleasure anticipated David, so that He might anoint him king by the hand of Samuel, justly declares that He found him.

It is afterwards added that He will be the guardian and protector of this kingdom of which He was the founder. For it is not His usual way to abandon His works after having begun them but, on the contrary, to carry them forward by a continued process of improvement to their completion.