Charles Ellicott Commentary Psalms 90:2

"Before the mountains were brought forth, Or ever thou hadst formed the earth and the world, Even from everlasting to everlasting, thou art God." — Psalms 90:2 (ASV)

Before the mountains. — This can be rendered either as,

“Before the mountains were born,
Or ever the earth and world were brought forth,”

in synonymous parallelism, or, better, in progressive,

“Before the mountains were born,
Or ever the earth and world brought forth”—

that is, before vegetation or life appeared. (Compare to Job 15:7.)

“Mountains” are a frequent symbol of antiquity, as well as of enduring strength. (Proverbs 8:25.)

The expression, “earth and the world,” may be taken as meaning the earth, as distinguished from either heaven or the sea, and the habitable globe (Septuagint, οἰκουμένη). (Compare to Proverbs 8:31.)

From everlasting to everlasting — that is, from an indefinite past to an indefinite future (literally, from hidden time to hidden).