'Unchangeable' in the Bible
But He is unchangeable, and who can turn Him? And what He wants to do, that He does.
For I have said, Mercy and loving-kindness shall be built up forever; Your faithfulness will You establish in the very heavens [unchangeable and perpetual].
This was so that, by two unchangeable things [His promise and His oath] in which it is impossible for God ever to prove false or deceive us, we who have fled [to Him] for refuge might have mighty indwelling strength and strong encouragement to grasp and hold fast the hope appointed for us and set before [us].