Isaiah 43:9

Isaiah pictured all the nations in this courtroom. Some had already assembled, and others were on their way. Who among them, the prophet asked, could proclaim former things? These "former things" probably refer to things predicted in the past that had since come to pass. [Note: See A. Schoors, I Am God Your Savior: A Form-Critical Study of the Main Genres in Is. XL-LV, pp. 94, 225.] No one among the nations, none of their gods, could predict the future and then bring it into existence. Only Yahweh could do this. Furthermore, no one could serve as a witness that the idols could do this or confirm the testimony of someone else that they could.

Undoubtedly some pagan prognosticators claimed to be able to foretell the future and that their predictions had come to pass, just as today some psychics make such claims. However, none of them could predict with the specificity and accuracy that Yahweh did through His prophets. The biblical prophecies that had already been fulfilled were in an entirely different class than the predictions that marked the nations. If this were not the case, Isaiah would not have dared to claim what he did here.