כי דבר סרה על ה' אלו-היכם המוציא אתכם מארץ מצרים, "for he has spoken perversely against the Lord your God Who has taken you out of the land of Egypt.⁠" In other words, the false prophet is guilty of insurrection against heaven even if he performed numerous miracles and placed the sun in the zenith of the sky (at morning or evening) and claimed that this was proof that God had instructed him to do so, so that on that particular day we are to serve a certain planet or constellation of stars or other celestial manifestations. Such an impostor is guilty of death by asphyxiation. The reason is that by doing what he did he challenged Moses's stature as God's foremost prophet (compare Maimonides Hilchot Yessodey Hatorah 9,5). By claiming to have received such instructions from God he violated the second of the Ten Commandments that "you shall not have any other deity.⁠" All of the people of Israel had heard this commandment directly from God with their own ears. How could anyone come later and claim that God had suspended this commandment even for a day?! All of Israel were witnesses against this so-called prophet even before he spoke. This is why the Torah decrees that such a person must be executed seeing all the "so-called" miracles he performed were not real but were deceptions of his audience, sleight of hand, power of suggestion, mass hypnosis, whatever you want to call it.

What we have said so far applies only when such a "prophet" asks the people or some of them to commit an act known to be forbidden as idolatrous. If however, a prophet, who had legitimised himself and had been proven to be a legitimate prophet for an extended period of time, will call on the people to temporarily disregard one of the other commandments of the Torah we must listen to him and continue to believe him and to follow his instructions seeing he made it clear that the suspension of the particular commandment he called for was only temporary. This is the meaning of the words אליו תשמעון, "to him you shall hearken" in Deut. 18,15 where the subject of prophets occurs once more. [if the prophet merely called upon you to perform the commandments of the Torah, the Torah would not have had to tell us that we must be "listening to him;⁠" we would be listening to God directly, without the need of a prophet's call. to do so. Ed.] If we do rely on the miracles performed by such a prophet and do not treat them as deception and sleight of hand this is because he has a חזקה, an established reputation, of being a true prophet. If for some reason unknown to us such a prophet becomes a renegade, the Torah does not consider our being misled by him as our fault, but wrote in Deut. 29,28 הנסתרות לה' אלו-הינו, "hidden matters are God's problem" (not our province to investigate). On the other hand הנגלות לנו ולבנינו, "matters which can be clarified by our using our means of detection, we ourselves are held responsible for.⁠" Man must judge by what his eyes see, only God is able to look into a man's heart (compare Maimonides Hilchot Yessodey Hatorah end of chapter 7). The Talmud Sanhedrin 90 also rules that when an established prophet such as Elijah at the time calls upon you to repair a private altar in order to discredit the priests of the Baal, we are to listen to such a prophet. The exception is if such a prophet were to ask you to commit an act of idolatry. The fact that Elijah offered a sacrifice outside the Temple, something prohibited in Leviticus 17,4 and 9, was prompted only by special circumstances.
Anyone arguing that a commandment should be canceled permanently is a false prophet seeing the commandments of the Torah (unless otherwise stated) are permanent This is the meaning of the last half of the verse we quoted from Deut. 29,28 לנו ולבנינו עד עולם לעשות את כל דברי התורה הזאת, "for us and for our children to carry out all the words of this Torah forever.⁠" What the sages said in respect of Elijah at Mount Carmel is applicable in all similar situations when prophets cancel Torah injunctions as an emergency measure. When Joshua (compare Bamidbar Rabbah 14,5) violated the Sabbath when the priests carrying the shofarot and the Holy Ark marched around Jericho for seven days in a row, he did so at the express command of God. This was an emergency. We encounter a similar occurrence with the prophet Elisha in Kings II 3,25 when the Israelites in their battle against Moav cut down fruit-bearing trees and stopped up wells. Although the Torah had expressly forbidden this in Deut. 20,19 the prophet used his authority to set aside this injunction on a temporary basis. If the prophet gives such orders and they sound as if they are meant to be permanent he has discredited himself and people must not listen to his instructions. This is the meaning of a statement in Yevamot 102: "if Elijah were to come and tell you that the rites of chalitzah are performed with a shoe known as מנעל one follows his instructions; if he were to instruct that this procedure must not be performed with a sandal instead, one does not follow his instructions.⁠" [The original practice had been to use a shoe known as מנעל. At the time of the Talmud, sandals had been in use for this for hundreds of years already. Even this established custom a prophet must not cancel permanently. Ed.]
The Talmud in Berachot 24,2 quotes a scholar saying that even if the greatest authority of his time had told him that it was permitted to recite the kriat shema in an otherwise unfit location by placing his hand over his mouth first, he would not obey this scholar in this matter. Moreover, the Talmud is also on record that even when such instructions are issued by means of a bat kol, a heavenly echo, this is without halachic significance when it involves permanent changes of Torah law. Prophecy is a higher authority than a בת קול and all the laws of the Torah have been communicated by the father of all prophets, by Moses. Rabbi Joshua used this latter statement in Baba Metzia 59 to aver that halachic decisions are arrived at by a majority of the competent scholars of their time and are not subject to divine interference (at a time when we have no prophets).