What does the Bible say about the faithfulness of God's word?

In Romans chapter 9, the Apostle Paul emphasizes that God's word is foundational and must not be doubted. He insists that, despite appearances to the contrary, God's purpose will always prevail. Paul quotes Old Testament prophets like Hosea and Isaiah to demonstrate that God's promises about salvation and His people are immutable. If God's word were to fail, then the assurance and hope of believers would be rendered meaningless, reflecting how vital it is for Christians to trust in the faithfulness of God’s word.