John Calvin Commentary Psalms 89:11

"The heavens are thine, the earth also is thine: The world and the fulness thereof, thou hast founded them." — Psalms 89:11 (ASV)

The heavens are thine, the earth also is thine. He again repeats, for the third time, that the same God who had been the deliverer of the chosen people exercises supreme dominion over the whole world. From the fact that God created all things, he concludes that it is He who actually presides over and controls whatever takes place in heaven and on earth.

It would be absurd to suppose that the heavens, having once been created by God, should now revolve by chance, or that things on earth should be thrown into confusion either by the will of humans or at random. Such a supposition is untenable when it is considered that it belongs to God to maintain and govern whatever He has created. Otherwise, like the pagans, we would imagine that He enjoys Himself in beholding all the works of His hand, in this beautiful theater of heaven and earth, without giving Himself any further trouble about them.

In speaking of the south and the north, and also of the mountains, Tabor and Hermon, the prophet accommodates his language to the common understanding of the people: as if he had said, there is no part of the fabric of the world that does not reverence and honor its Creator.

I also connect with this the next verse, which affirms that the arm of God is furnished with power, his hand with strength, and that his right hand is exalted. Some interpret the last two clauses of the verse as a prayer: Strengthen thy hand, lift up thy right hand; but this seems too far removed from the prophet's meaning, who, with the simple aim of encouraging all the godly, celebrates the inconceivable power of God.