What shall one then answer...? — The words obviously imply that the prophet either had received, or expected to receive, a message of inquiry from the Philistines, and that this is his answer. It seems not improbable, indeed, that the series of prophecies that follow were delivered in answer to such inquiries. The fame of the prophet had spread beyond the confines of Israel, and men of different nations came to Jerusalem to consult him. So Jeremiah’s oracles are delivered to the ambassadors who came to propose an alliance against Nebuchadnezzar in the time of Zedekiah (Jeremiah 27:3). Commonly, however, the words are referred to the embassies of congratulation, which came with plans of new alliances after the destruction of Sennacherib’s army (2 Chronicles 32:23).
That the Lord hath founded Zion. — This is the answer to all such inquiries. Zion stands firm and safe in the protection of Jehovah. The “poor” (obviously those of Isaiah 14:30) shall trust (better, shall find refuge) in it. (Comp. Isaiah 28:16.) They need no foreign alliances, no arm of flesh.