Prophet Says to Kill Obey?

 Radvaz (2:652): Question: We have an established principle that if an established prophet should command us to transgress one of the mitzvos of the Torah except for idolatry we are to listen to him. For example Eliyahu on Mt. Carmel transgressed on the command not to offer sacrifices outside of the Temple. He didn’t do this to nullify the mitzva but rather as an emergency measure to refute the prophets of Baal. Your question is whether such a prophet said to kill someone or destroy a particular city or to pillage a particular city as an emergency measure to protect the Torah – how can we obey such a command since no court would do such a thing even as an emergency measure? And even if it were commanded by G d – but we have the principle of “it is not in Heaven”? Since a person is not killed except with witnesses and with proper warning – how is it possible to listen to the prophet to transgress that which is stated in the Torah? Even if he gives an explanation for the need to do this – that would not be sufficient – but he says it is a mitzva to listen to him according to the Torah. Answer: Also in my eyes this is was puzzling until it occurred to me to say that this principle only applies to mitzvos between man and G d. But concerning mitzvos between men, there is no command to listen to him. However I saw in Sanhedrin: Concerning all sins if a prophet tells you to transgress the words of Torah you are to listen to him except for idolatry, because it is possible that he has the ability to stop the sun in the middle of the sky so don’t listen to him…. Thus this gemora clearly states that the only sin not to commit at the command of a prophet is idolatry