Isaiah 39:4 - Exposition

What have they seen? Isaiah had, no doubt, heard of what Hezekiah had done (verse 2); but he wished to have the confession of it from his own mouth before delivering his sentence. Hezekiah tells him the truth, since he is not ashamed of his act, but rather glories in it. He has shown the ambassadors everything, and has thereby made them eager to secure his alliance.