You can never do better than to read Spurgeon’s commentary on the Psalms, his Treasury of David. In the wee hours I could not sleep and read his commentary on Psalm 90. Read it here.
Here is what Luther wrote about Psalm 90:
Such a God (he says) have we, such a God do we worship, to such a God do we pray, at whose command all created things sprang into being. Why then should we fear if this God favours us? Why should we tremble at the anger of the whole world? If He is our dwelling place, shall we not be safe though the heavens should go to wrack? For we have a Lord greater than all the world. We have a Lord so mighty that at his word all things sprang into being. And yet we are so fainthearted that if the anger of a single prince or king, nay, even of a single neighbour, is to be borne, we tremble and droop in spirit. Yet in comparison with this King, all things beside in the whole world are but as the lightest dust which a slight breath moves from its place, and suffers not to be still. In this way this description of God is consolatory, and trembling spirits ought to look to this consolation in their temptations and dangers.