Peter Pett's Commentary on the Bible
Isaiah 39 - Introduction
Chapter 39 Visitors From Babylon.
‘At that time.' That is at the time of his having received the sign from God and having gone up to the house of Yahweh to acknowledge and give thanks for His power. What better time for ambassadors from Babylon to arrive? Surely he would now tell them to be on their way because God was able to deliver Jerusalem and Judah from the Assyrian yoke. God had primed him up and had given him two remarkable signs, his extension of life and God's revelation of His power over the sun. How then could he do otherwise? But as this chapter demonstrates, he did do otherwise.
In human terms it is understandable. While Hezekiah was highly esteemed among the local peoples, he could not be compared to a king of Babylon. And he must have been highly flattered that that great king should seek him out and ask after his welfare and desire an alliance with him. We are given to understand that he was right to welcome them, but that that should have been all. Indeed we are given the picture of Isaiah waiting apprehensively, wondering what choice he would make.
And he chose disastrously. He unbared all his treasures and armour to the ambassadors, a clear indication that he was offering his strength to back up the rebellion. It was fatal. Not only did it mean that he was putting his trust in alliances with godless nations, and especially godless Babylon, rather than in Yahweh, but it also showed Babylon what treasures he had. And the wise old Isaiah knew instinctively that to a great and arrogant city like Babylon this could only be like a light to a moth, drawing it onwards until the glittering treasures were its own.
Of what purpose then had been God's miraculous sign? Ahaz had refused the sign. Hezekiah had received the sign and then ignored its significance. Both were as bad. The house of David had rejected its second chance.