But thou, O Lord, shalt endure for ever - Though my condition has been changed, though I have been cast down from an exalted position, though kingdoms rise and fall, yet thou art unchanged. Thy purposes will abide. Thy promises will be fulfilled. Thy character is the same. As thou hast been the hearer of prayer in past times, so thou art now. As thou hast interposed in behalf of thy people in other ages, so thou wilt now. As thy people in affliction have been permitted to come to thee, so they may come to thee now. The psalmist here brings to his own mind, as an encouragement in trouble, as we may at all times, the fact that God is an unchanging God; that he always lives; that he is ever the same. We could have no ground of hope if God changed; if he formed purposes only to abandon them; if he made promises only to disregard them; if today he were a Being of mercy and goodness, and tomorrow would be merely a Being of justice and wrath. This argument is enlarged upon in Psalms 102:25-28.
And thy remembrance unto all generations - Thy memory; or, the remembrance of thee. My days are like a shadow. I shall pass away, and be forgotten. No one will recollect me; no one will feel any interest in remembering that I have ever lived (see the notes at Psalms 31:12). But while one knows that this must be so in regard to himself and to all other people - that he and they are alike to be forgotten - he may also feel that there is One who will never be forgotten. God will never pass away. He will be always the same. All the hopes of the church - of the world - are based on this. It is not on man - on any one individual - on any number of people - for they will all alike pass away and be forgotten; but one generation of people after another, to the end of time, may call on God, and find him an ever-living, an unchanged and unchangeable protector and friend.