2 Chronicles 32:1-3

1After these things and this faithfulness, Sennacherib king of Assyria came and invaded Judah and besieged the fortified cities, intending to take them for himself.

2When Hezekiah saw that Sennacherib had come and that he intended to go to war against Jerusalem,

3he decided, together with his officers and his soldiers, to stop up the water [supply] from the springs which were outside the city [by enclosing them with masonry and concealing them], and they helped him.