Eze 14:9 And if the prophet be deceived when he hath spoken a thing, I the LORD have deceived that prophet, and I will stretch out my hand upon him, and will destroy him from the midst of my people Israel.

A little commentary on this neglected verse: we have a real example of this in the case of Jehoshaphat the king of Judah. He summons 400 prophets to tell him what to do. When he gets a real prophet of God (Micaiah), that prophet begins by sarcastically saying the same thing that the false prophets were saying:

1Ki 22:15 So he came to the king. And the king said unto him, Micaiah, shall we go against Ramothgilead to battle, or shall we forbear? And he answered him, Go, and prosper: for the LORD shall deliver it into the hand of the king.

But after the King presses Micaiah, Micaiah tells him the truth. God has sent lying spirits into the 400 prophets in order to kill Ahab. Ahab, less than impressed, proceeds to ignore Micaiah and get himself killed, fulfilling God’s intent in deceiving the 400 prophets.