Charles H. Spurgeon on Psalms 89:2

For I have said, Mercy shall be built up for ever. His heart was persuaded of it, and he had affirmed it as an indisputable truth. He was certain that upon a sure foundation the Lord intended to pile up a glorious palace of goodness —a house of refuge for all people, wherein the Son of David should for ever be glorified as the dispenser of heavenly grace. Thy faithfulness shalt thou establish in the very heavens. This divine edifice, he felt assured, would tower into the skies, and would be turreted with divine faithfulness even as its foundations were laid in eternal love. God's faithfulness is no thing of earth, for here nothing is firm, and all things savour of the changes of the moon and the fickleness of the sea: heaven is the birthplace of truth, and there it dwells in eternal vigour. As the blue arch above us remains unimpaired by age, so does the Lord's truth; as in the firmament he hangs his covenant bow, so in the upper heavens the faithfulness of God is enthroned in immutable glory. This Ethan said, and this we may say; come what will, mercy and faithfulness are built up by "the Eternal Builder", and his own nature is the guarantee for their perpetuity. This is to be called to mind whenever the church is in trouble, or our own spirits bowed down with grief.