2 Chronicles 32:4

So there was gathered much people together
At the instance of Hezekiah, his nobles and officers:

who stopped all the fountains;
perhaps by laying planks over them, and earth upon them, so that it could not be discerned there were any fountains there:

and the brook that ran through the midst of the land;
which, according to Kimchi, was Gihon, ( 2 Chronicles 32:30 ) , which was near Jerusalem; the stream of this very probably they turned into channels under ground, whereby it was brought into the city into reservoirs there provided, that that might have a supply during the siege, while the enemy was distressed for want of it:

saying, why should the kings of Assyria come and find much water?
by which means they would be able to carry on the siege to a great length, when otherwise they would be obliged to raise it quickly: mention is made of kings of Assyria, though there was but one, with whom there might be petty kings, or tributary ones; and, besides, as he boasted, his princes were altogether kings, ( Isaiah 10:8 ) .