Leviticus 24:16

24:16 and one who misuses the name of the Lord must surely be put to death. The whole congregation must surely stone him, whether he is a foreigner or a native citizen; when he misuses the Name he must be put to death.

Deuteronomy 18:20

18:20 “But if any prophet presumes to speak anything in my name that I have not authorized him to speak, or speaks in the name of other gods, that prophet must die.