(Verse 4) And he said: What did they see in your house? And Hezekiah said: They saw everything that is in my house; there was nothing, neither word nor thing, that I did not show them in my treasures. And Isaiah said again, 'What did they see in your house?' And he answered truthfully that they had seen everything in his house, and that he had not withheld anything from them in his treasuries. But he kept silent about the other, which he feared would offend them, because he had shown them everything he had in his power, undoubtedly including the furnishings of the Temple.
Source: Commentary on Isaiah