Before the mountains were brought forth, or ever you had formed the earth and the world, from everlasting to everlasting you are God.
Moses opens by anchoring the people to God's covenant favor before he addresses their misery and judgment. He means to say: yes, you die like all men, yes, God punishes sin, but He has adopted you, and that peculiar grace is your true dwelling place through all generations.
AI summary
Commenting on Psalm 90:1-17
Before the mountains were brought forth. Before those elder giants had struggled forth from nature's womb, as her dread firstborn, the Lord was glorious and self sufficient. Mountains to him, though hoar with the snows of ages, are but new born babes, young things whose birth was but yesterday, mere novelties of an hour. Or ever thou hadst formed the earth and the world.
This psalm is entitled a prayer of Moses. Where, and in what volume, it was preserved from Moses's time till the collection of psalms was begun to be made, is uncertain; but, being divinely inspired, it was under a special protection: perhaps it was written in the book of Jasher, or the book of the wars of the Lord.
Commenting on Psalm 90:1-6