Deuteronomy 23:9

And ye, in any wise keep yourselves from the accursed thing, lest ye make yourselves accursed, when ye take of the accursed thing, and make the camp of Israel a curse, and trouble it.

Israel hath sinned, and they have also transgressed my covenant which I commanded them: for they have even taken of the accursed thing, and have also stolen, and dissembled also, and they have put it even among their own stuff. Therefore the children of Israel could not stand before their enemies, but turned their backs before their enemies, because they were accursed: neither will I be with you any more, except ye destroy the accursed from among you. Up, sanctify the people, and say, Sanctify yourselves against to morrow: for thus saith the LORD God of Israel, There is an accursed thing in the midst of thee, O Israel: thou canst not stand before thine enemies, until ye take away the accursed thing from among you.

And Jehoshaphat dwelt at Jerusalem: and he went out again through the people from Beersheba to mount Ephraim, and brought them back unto the LORD God of their fathers.

And Jehoshaphat feared, and set himself to seek the LORD, and proclaimed a fast throughout all Judah. And Judah gathered themselves together, to ask help of the LORD: even out of all the cities of Judah they came to seek the LORD. And Jehoshaphat stood in the congregation of Judah and Jerusalem, in the house of the LORD, before the new court, And said, O LORD God of our fathers, art not thou God in heaven? and rulest not thou over all the kingdoms of the heathen? and in thine hand is there not power and might, so that none is able to withstand thee? Art not thou our God, who didst drive out the inhabitants of this land before thy people Israel, and gavest it to the seed of Abraham thy friend for ever? And they dwelt therein, and have built thee a sanctuary therein for thy name, saying, If, when evil cometh upon us, as the sword, judgment, or pestilence, or famine, we stand before this house, and in thy presence, (for thy name is in this house,) and cry unto thee in our affliction, then thou wilt hear and help. And now, behold, the children of Ammon and Moab and mount Seir, whom thou wouldest not let Israel invade, when they came out of the land of Egypt, but they turned from them, and destroyed them not; Behold, I say, how they reward us, to come to cast us out of thy possession, which thou hast given us to inherit. O our God, wilt thou not judge them? for we have no might against this great company that cometh against us; neither know we what to do: but our eyes are upon thee. And all Judah stood before the LORD, with their little ones, their wives, and their children.

And thus did Hezekiah throughout all Judah, and wrought that which was good and right and truth before the LORD his God.

After these things, and the establishment thereof, Sennacherib king of Assyria came, and entered into Judah, and encamped against the fenced cities, and thought to win them for himself. And when Hezekiah saw that Sennacherib was come, and that he was purposed to fight against Jerusalem, He took counsel with his princes and his mighty men to stop the waters of the fountains which were without the city: and they did help him. So there was gathered much people together, who stopped all the fountains, and the brook that ran through the midst of the land, saying, Why should the kings of Assyria come, and find much water? Also he strengthened himself, and built up all the wall that was broken, and raised it up to the towers, and another wall without, and repaired Millo in the city of David, and made darts and shields in abundance. And he set captains of war over the people, and gathered them together to him in the street of the gate of the city, and spake comfortably to them, saying, Be strong and courageous, be not afraid nor dismayed for the king of Assyria, nor for all the multitude that is with him: for there be more with us than with him: With him is an arm of flesh; but with us is the LORD our God to help us, and to fight our battles. And the people rested themselves upon the words of Hezekiah king of Judah. After this did Sennacherib king of Assyria send his servants to Jerusalem, (but he himself laid siege against Lachish, and all his power with him,) unto Hezekiah king of Judah, and unto all Judah that were at Jerusalem, saying, Thus saith Sennacherib king of Assyria, Whereon do ye trust, that ye abide in the siege in Jerusalem? Doth not Hezekiah persuade you to give over yourselves to die by famine and by thirst, saying, The LORD our God shall deliver us out of the hand of the king of Assyria? Hath not the same Hezekiah taken away his high places and his altars, and commanded Judah and Jerusalem, saying, Ye shall worship before one altar, and burn incense upon it? Know ye not what I and my fathers have done unto all the people of other lands? were the gods of the nations of those lands any ways able to deliver their lands out of mine hand? Who was there among all the gods of those nations that my fathers utterly destroyed, that could deliver his people out of mine hand, that your God should be able to deliver you out of mine hand? Now therefore let not Hezekiah deceive you, nor persuade you on this manner, neither yet believe him: for no god of any nation or kingdom was able to deliver his people out of mine hand, and out of the hand of my fathers: how much less shall your God deliver you out of mine hand? And his servants spake yet more against the LORD God, and against his servant Hezekiah. He wrote also letters to rail on the LORD God of Israel, and to speak against him, saying, As the gods of the nations of other lands have not delivered their people out of mine hand, so shall not the God of Hezekiah deliver his people out of mine hand. Then they cried with a loud voice in the Jews' speech unto the people of Jerusalem that were on the wall, to affright them, and to trouble them; that they might take the city. And they spake against the God of Jerusalem, as against the gods of the people of the earth, which were the work of the hands of man. And for this cause Hezekiah the king, and the prophet Isaiah the son of Amoz, prayed and cried to heaven. And the LORD sent an angel, which cut off all the mighty men of valor, and the leaders and captains in the camp of the king of Assyria. So he returned with shame of face to his own land. And when he was come into the house of his god, they that came forth of his own bowels slew him there with the sword. Thus the LORD saved Hezekiah and the inhabitants of Jerusalem from the hand of Sennacherib the king of Assyria, and from the hand of all other, and guided them on every side.