Psalms 119:89

Here, 1. The psalmist acknowledges the unchangeableness of the word of God and of all his counsels: "For ever, O Lord! thy word is settled. Thou art for ever thyself (so some read it); thou art the same, and with thee there is no variableness, and this is a proof of it. Thy word, by which the heavens were made, is settled there in the abiding products of it;" or the settling of God's word in heaven is opposed to the changes and revolutions that are here upon earth. All flesh is grass; but the word of the Lord endures for ever. It is settled in heaven, that is, in the secret counsel of God, which is hidden in himself and is far above out of our sight, and is immovable, as mountains of brass. And his revealed will is as firm as his secret will; as he will fulfil the thoughts of his heart, so no word of his shall fall to the ground; for it follows here, Thy faithfulness is unto all generations, that is, the promise is sure to every age of the church and it cannot be antiquated by lapse of time. The promises that look ever so far forward shall be performed in their season. 2.

— Matthew Henry's Concise Commentary (public domain)