What did Hezekiah do when envoys came from the king of Babylon?

Answer: Showed them all his treasures

When envoys of Merodach-baladan king of Babylon visited, Hezekiah showed them everything in his treasure house and armory.

“And Hezekiah received the envoys and showed them all that was in his treasure house—the silver, the gold, the spices, and the precious oil, as well as his armory—all that was found in his storehouses. There was nothing in his palace or in all his dominion that Hezekiah did not show them.”— 2 Kings 20:13 (BSB)