Matthew Henry Commentary Psalms 89:1-4

"I will sing of the lovingkindness of Jehovah for ever: With my mouth will I make known thy faithfulness to all generations. For I have said, Mercy shall be built up for ever; Thy faithfulness wilt thou establish in the very heavens. I have made a covenant with my chosen, I have sworn unto David my servant: Thy seed will I establish for ever, And build up thy throne to all generations. Selah" — Psalms 89:1-4 (ASV)

Though our expectations may be disappointed, yet God's promises are established in the heavens, in His eternal counsels; they are out of the reach of opposers in hell and earth. And faith in the boundless mercy and everlasting truth of God may bring comfort even in the deepest trials.