A prophet who 'speaks in the name of the L-rd' has a tremendous burden. What he says must come true 100% of the time. If anything in his prophecy is false, it is considered false prophecy. And we know what the Torah says about such false prophets.
As our Sage Rambam (Maimonides) writes:
http://www.askmoses.com/en/article/248,2100910/What-are-the-requirements-of-a-true-prophet.htmlChapter 71) One of the bases of religion is to know that G-d visits people in prophetic visions, which come only to exceedingly wise people of outstanding characteristics, whose inclinations never lead them to earthly matters but who always conquer their inclinations, and who are of correct temperaments. A person who fulfils these criteria, and is of perfect health, will, when studying esoterical philosophy and is attracted by those elevated issues and is of an appropriate temperament to understand and comprehend them , and sanctifies himself by moving away from anybody who concerns himself with ephemeral matters, and encourages himself not to have any thoughts about useless matters and its contrivances, have his thoughts permanently attuned to above, from under G-d's Throne, to understand the pure and holy forms, and looks upon the wisdom of G-d [in Creation] in its entirety, from the first form [i.e the Holy Chayot] till the centre of the Earth, and sees in them G-d's greatness, and then prophecy will immediately come to him. At the time when prophecy comes to him, his soul will be on the same level as that of the Ishim angels, and he will become a different man, and he will realize that he is not [any more] as he was, but will rise above the level of other wise men, as it is written, "...and you shall prophesy with him, and shall be turned into another man".
2) There are [many] levels of prophecy - in the same way that one person can be wiser than another, so can he be more prophetic. Prophetic insights come only in nocturnal visions in dreams, or by day after falling asleep, as it is written, "I the L-rd make Myself known to him in a vision, and speak to him in a dream". Whenever one is receiving a prophecy, one's limbs shake, the strength of one's body weakens, and one's thoughts become disturbed, leaving one's mind free to understand what one will see, as it is written in connection with Abraham, "...and, lo, a horror of great darkness fell upon him", and as it is written in connection with Daniel, "...for my comely appearance was horribly changed, and I retained no strength".
3) What is made known to a prophet during prophecy is done so by way of parable, and he will immediately realize what the parable means. For instance, when Jacob the Patriarch saw the ladder with angels ascending and descending it, it was a parable representing monarchy and its subjection. Similarly, the animals which Ezekiel saw, the boiling pot and almond tree which Jeremiah saw, and all the other objects seen by the other Prophets were also parables. Of the Prophets, some, like those mentioned above, related what they saw in their prophecy and their interpretation of it, whereas some related just their interpretation. Sometimes they related just the parables [of the prophecy], like Ezekiel and Zachariah sometimes did. All of the Prophets prophesized by way of parables and riddles.
4) None of the Prophets receive prophecies whenever they wanted, but they would attune their thoughts, be happy and of a good heart, and seek solitude, for prophecy does not come to those who are sad or lazy, but only to those who are happy. Therefore, the sons of prophets would have before them harps, drums and flutes, and would seek prophecy, as it is written, "...and they shall prophesy", that is to say that they will follow the ways of prophecy until they prophesize, progressing as they go.
5) Those who seek prophecy are called the sons of prophets. Even though they attune their thoughts, the Divine Presence may, or may not, inspire them.
6) All the Prophets, from the first to the last, prophesized in these ways, with the exception of Moses our Teacher, chief of the Prophets. In what ways did Moses differ from the other Prophets? Firstly, whereas the other Prophets received their prophecies in a dream or vision, Moses received his while awake and standing, as it is written, "And when Moses was in the Tent of Meeting to speak with Him, he heard the voice speaking to him, et cetera". Secondly, the other Prophets received their prophecies via an angel. Therefore, what they saw was by way of parable and riddle. Moses, on the other hand, did not receive his prophecies via an angel, as it is written, "With him I speak mouth to mouth", "And the L-rd spoke to Moses face to face", "...and the outward appearance of the L-rd does he behold", that is to say that what Moses saw what not by way of parable, but he saw each prophecy absolutely clearly without any parables or riddles. The Torah said about him, "...manifestly, and not in dark speeches", showing that when Moses received a prophecy he did not do so by way of riddles, but did so with clarity, and saw everything absolutely clearly. Thirdly, the other Prophets were scared [of their prophetic visions] and would shy away, but Moses wasn't and didn't. Scripture says, "...as a man speaks with a friend" - just as a man is not scared to listen to his friend, so Moses had the capabilities to understand his prophecies and to stand unafraid. Fourthly, none of the Prophets prophesized whenever they wanted to, but whenever G-d wanted to He would visit Moses and bestow upon him prophecy. Moses did not have to attune his thoughts or otherwise prepare himself, for the reason that he was always prepared and stood like a ministering angel. Therefore, he would receive prophecies at any time, as it is written, "Stand still and I will hear what the L-rd will command concerning you". In this G-d trusted him, as it is written, "Go say to them, `Return to your tents'. But as for you, stand here by Me, and I will speak to you, et cetera". From here we see that whenever any of the other Prophets had finished prophesizing they would return to their houses [and families] and other bodily needs, like everybody else, so they therefore did not separate themselves from their wives. Moses, on the other hand, did not return to his home, and separated himself from his wife, and all that resembled her, for ever. His mind was [always] connected to G-d, and G-d's glory never left him at all; light emanated from his face, and he was holy like an angel.
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Chapter 9
1) It is explicitly and clearly stated in the Torah that it [the Torah] is an everlasting Mitzvah, and cannot be changed, subtracted from or added to, as it is written, "Every matter which I command you observe to do it; you shall not add to it, or subtract from it", and it is also written, "...but those things which are revealed belong to us and to our children for ever, that we may do all the words of the Torah". From here we see that we have been commanded to keep all the commandments of the Torah for always. In connection with this it is written, "...a statute for ever throughout your generations", and it is also written, "It is not in heaven". From here we see that a prophet may not make any changes [at all] in the Torah. Therefore, if a man, whether a gentile or a Jew, arises and performs signs and wonders, and says that G-d sent him to add to, or take away from, a mitzvah, or to institute a new mitzvah which we did not hear from Moses, or says that the commandments with which we have been commanded are not for eternity but are meant only for a temporary period, then he is a false prophet, for he has come to undermine the prophecy of Moses. His punishment is death by strangulation, which is the punishment for deliberately speaking in the name of G-d without having been commanded to do so. G-d told Moses that all the commandments are for eternity, and no man can accuse G-d of being deceitful.
2) If so, why is it written in the Torah, "I will raise up for them a prophet from amongst their brethren, like you, and will put My words in his mouth, and he shall say to them all that I shall command him"? The prophet in question does not come to start a [new] religion, but to reiterate the commandments of the Torah and to warn the people not to transgress them, as the last Prophet said, "Remember the Torah of Moses My servant". Similarly, if he gave us commandment in optional matters, such as by saying, `Go (or don't go) to such-and-such a place', or, `Start (or don't start) a war today', or, `Build (or don't build) a wall here', et cetera, we are commanded to listen to him, and anyone who doesn't is liable to death at the hands of G-d, for it is written, "And it shall come to pass, that whoever will not listen to My words which he shall speak in My Name, I will require it of him".
3) Similarly, a prophet who himself transgresses his own words, and a prophet who ignores his prophecy [and does not deliver it], are also liable to death at the hands of G-d, for it is written, "I will require it of him". Similarly, if a prophet who is known to be a [true] prophet tells us to transgress one, or many, of the commandments of the Torah, whether of the stringent or of the more lenient ones, but only as a temporary practice, then we are commanded to listen to him. So we learnt from the first Sages, that we should listen to a prophet whatever the commandments he tells us to transgress are, as with Elijah at Mount Carmel, except if the commandment he tells us to transgress is that of not practicing idolatry, and provided that he tells us to transgress only as a temporary practice, like Elijah did at Mount Carmel, when he offered sacrifices outside Jerusalem, which is the city chosen for offering sacrifices in, and anyone who does so outside Jerusalem is liable to karet. Even so, since Elijah was a prophet, it was a mitzvah to listen to him. The verse, "...to him you shall listen" applies also in situations like the one with Elijah. Had the people asked Elijah how he could violate the Torah verse of, "Take heed to yourself that you do not offer your burnt offerings in any place that you see", he could have told them that anyone offering sacrifices outside the Temple is liable to karet, in accordance with what Moses commanded, but he was offering sacrifices outside the Temple in accordance with what G-d had said to him, and in order to discredit the prophets of Ba'al. In this manner we are commanded to listen to any prophet who tells us to transgress as a temporary measure. If he tells us that a commandment of the Torah is to be abolished for ever, then his punishment is death by strangulation, for it is written, "...belong to us and to our children for ever".
4) Similarly, if he tries to abolish [for ever] a Rabbinical institution or decree, or, concerning one of the Laws of the Torah he says that G-d commanded for the Law to be one way,, but we practice [in a different way] according to the words of so-and-so, then he is a false prophet and is put to death by strangulation, even if he shows a sign, for he is trying to disprove the Torah's statement of, "It is not in heaven". If, however, he said that we should do what he says only as a temporary measure, we listen to him.
5) This is talking about any commandment other than the one not to serve idols, for if he told us to serve idols we do not listen to him, even if he told us to do so only as a temporary measure. Even if he performed great signs and wonders and says that G-d has commanded that we serve idols on a particular day, or at a particular hour, he is trying to turn us away from G-d, and about this it is written, "And the sign or wonder come to pass...you shall not listen to the words of that prophet...because he has spoken to turn you away from the L-rd your G-d", for he is trying to disprove the prophecy of Moses. Therefore, we know for sure that he is a false prophet, and that all his signs are the result of spells and witchcraft, and he must be put to death by strangulation.
Chapter 10
1) Any prophet who arises and says that G-d sent him does not have to perform a sign of the type that Moses, Elijah or Elishah did, which involved supernatural events. Instead, the sign that he has to perform is to predict the future, and we have to believe him, as it is written, "And if you say in your heart, `How shall we know the word which the L-rd has not to spoken?'". Therefore, when a man suitable for prophecy comes in the Name of G-d, without wanting to add to or take away from, any of the commandments, but wants us to serve G-d properly, we do not ask him to split the sea, or to resurrect the dead, or to perform some other supernatural event, and then believe him, but we tell him to predict the future because he is a prophet, which he does, and we wait to see if what he says happens or not. Even if was wrong in only a small matter, he is a false prophet, but if all of what he said comes true, then he is believed.
2) A prophet has to be checked many times. If all his words are true then he is a prophet, as it says with respect to Samuel, "And all Israel, from Dan to Be'er-Sheva, knew that Samuel was accredited as a prophet of the L-rd".
3) Enchanters and diviners also predict the future, so how do they differ from a prophet? Of what enchanters and diviners say some comes true and some does not, as it is written, "Let now the astrologers, the stargazers, the monthly prognosticators, stand up, and save you from these things shall come upon you" - it says, "from these things", and not, "from all these things", so it is possible that not all of what they said will come true, and that they were mistaken in everything, as it is written, "...that frustrates the omens of imposters, and makes diviners mad". With respect to a [true] prophet, all of what he says comes true, as it is written, "Know now that nothing shall fall to the earth of the word of the L-rd", and it is also written, "The prophet that has a dream, let him tell a dream; and he that has My word, let him speak My word faithfully. What is the chaff of the wheat? says the L-rd", that is to say that the words of diviners is like some chaff into which some wheat has been mixed, whereas the words of the L-rd are completely true, with no falsehoods at all. This is backed up by Scripture, which says that prognosticators and diviners deceive the nations with their words, but a prophet makes known truthful matters, and we do not have to enchant or divine [to verify his words], for it is written, "There must not be found among you anyone that makes his son or his daughter pass through the fire...for these nations...The L-rd your G-d will raise up for you a prophet from amongst you". From here we see that a prophet makes known only earthly matters, such as famine or plenty, war or peace, and similar things. Prophets even answer the needs of the one, such as when Saul had lost an item and went to a prophet to help him find it. A prophet may say what he wants provided that he does not start another religion, add a mitzvah or take one away.
If a man says that G-d sent him to add to, or take away from, a mitzvah, or to institute a new mitzvah which we did not hear from Moses, then he is a false prophet
4) If a prophet predicts something bad, such as that so-and-so will die, or that this year will be one of war or famine, et cetera, and his prediction did not come true, then it is not a disproof of his prophecy and we do not label him as a false prophet, for the reason that G-d is exceedingly merciful and [often] revokes bad decrees, so it is possible that those on whom evil had been decreed had, like the citizens of Nineveh, repented, or had had their decree suspended, as with Hezekiah. But if, however, the prophet decreed good things and his prediction did not come true, then he is definitely a false prophet, for whenever G-d makes a good decree, even if it is conditional, He does not revoke it. From here we see that a prophet is tested only with respect to good matters. This is what Jeremiah said in his answer to Hananiah the son of Azur, when Jeremiah was prophesizing bad things and Hananiah good things: `If what I say does not come true, it is not a sign that I am a false prophet, but if what you say does not come true, it shows that you are a false prophet', for it is written, "Nevertheless, hear now this word...As for the prophet who prophecies for peace, when the word of that prophet shall come to pass, then shall it be known that the L-rd has truly sent the prophet".
