Albert Barnes Commentary Psalms 102:25-27

"Of old didst thou lay the foundation of the earth; And the heavens are the work of thy hands. They shall perish, but thou shalt endure; Yea, all of them shall wax old like a garment; As a vesture shalt thou change them, and they shall be changed: But thou art the same, And thy years shall have no end." — Psalms 102:25-27 (ASV)

Long ago - See this passage fully explained in the notes at Hebrews 1:10-12. In the beginning; at the first. The phrase used here means literally “to the face;” then, “before” in the order of time. It means here, long ago; in ancient times; at the beginning. The meaning is that God’s years have stretched through all generations of people and all the changes that have occurred on the earth, and that he existed at the very beginning and will continue to exist to the very end, unchangeably the same.