Yahweh summons the nations to bring their witnesses to vindicate themselves (Isaiah 43:9), but Israel is the chief witness in His defense (43:9, 10, 12; 44:8, 9). How?

Isaiah 44:8 appears to give the answer:

Yahweh long ago announced what He would do and declared it. He promised, for instance, to give the land of Canaan to Abraham, and explained the process by which Abraham’s seed would inherit the land (Genesis 15). He promised (through Isaiah) to bring Israel back from Babylonian bondage. He speaks about things that are not yet.

Israel preserves the testimony of Yahweh’s promises and commitments. The Scriptures document that God has spoken before things happened. Israel’s Scriptures her use of them in teaching, song, ritual preserve the testimony that Yahweh has spoken.

And then the things not yet happen. Israel comes out of Egypt and inherit the land, and they return from Babylon. Events vindicate Yahweh’s promises. Events vindicate Israel’s trust in Yahweh. And so in the sheer facts of Israel’s history, Israel becomes a witness in defense of Yahweh.

Israel witnesses to the uniqueness of Yahweh. For what other God can speak 400 years before the event and then bring that promise to pass? Who can make commitments long ahead of time and then keep them? What other God is at the beginning and at the end, at the first and at the last? What other God encloses and encompasses all time? There is none, Israel’s history tells us. Yahweh alone is God.