2 Chronicles 32:2-5

Now when Hezekiah saw that Sennacherib had come and that he intended to make war on Jerusalem, he decided with his officers and his warriors to cut off the supply of water from the springs which were outside the city, and they helped him. So many people assembled and stopped up all the springs and the stream which flowed through the region, saying, “Why should the kings of Assyria come and find abundant water?” And he took courage and rebuilt all the wall that had been broken down and erected towers on it, and built another outside wall and strengthened the Millo in the city of David, and made weapons and shields in great number.