Daniel 4:26

Shall be sure. Many have wondered why the insane king was not killed, or why his subjects and ministers of state did not place someone else on the vacant throne during the time Nebuchadnezzar was incapacitated. The following explanation has been offered: Superstitious ancients thought that all mental disturbances were caused by evil spirits who took control of their victim; that if someone should kill the insane man, the spirit would take hold of the murderer or instigator of the crime; and that if his property should be confiscated or his office filled, a grievous revenge would be inflicted upon those responsible for the injustice. For this reason insane persons were removed from the society of men, but otherwise not molested (see 1 Samuel 21:12 to 1 Samuel 22:1).