But the prophet who presumes to speak a word in my name
which I have not commanded him to speak,
or who speaks in the name of other gods,
that same prophet shall die.
And if you say in your heart,
"How may we know the word which the LORD has not spoken?" --
when a prophet speaks in the name of the LORD,
if the word does not come to pass or come true,
that is a word which the LORD has not spoken;
the prophet has spoken it presumptuously,
you need not be afraid of him.
[Deut 18:19-22] You also need not sign over your life's savings to him, unless, of course, you're a glutton for punishment.