These are the commandments and regulations that Hashem commanded Bnai Yisrael through Moshe on the Plains of Moav, on the Yardain (Jordan River) opposite Yericho. (Sefer BeMidbar 36:13)
These are the commandments that Hashem commanded Moshe for Bnai Israel at Mount Sinai. (Sefer VaYikra 27:34)
1. The similar endings of Sefer VaYikra and Sefer BeMidbar This first of the above passages is the final passage in Sefer BeMidbar. The passage is very similar to the second passage which is the final passage in Sefer VaYikra. The passage in Sefer VaYikra is the source of an important lesson. The Sages explain that the passage teaches us that a prophet is not authorized to add to the commandments of the Torah. Targum Yonatan Ben Uziel actually includes this lesson in his rendering of the passage. He renders the passage: These are the commandments that Hashem commanded Moshe and it is not possible to create within them any new element etc. Apparently, he maintains that the phrase “these are the laws” indicates that these alone are the laws and that no new laws can be attributed to revelation.
It is not clear why Sefer BeMidbar requires a similar closing. However, the comments of Malbim may be relevant to this issue. He explains that the passage in the end of Sefer BeMidbar refers two categories of laws – mitzvot and mishpatim – that were taught to Bnai Yisrael on the Plains of Moav. Malbim explains that “mitzvot” refers to the various commandments that relate to our relationship with Hashem. “Mishpatim” refers to laws that govern our relationships with one another. In addition to the commandments that Moshe taught Bnai Yisrael when he descended from Sinai, Moshe expounded various laws of these two types on the Plains of Moav. Malbim further explains that our Sages dispute the origin of the laws taught to the people on the Plains of Moav. All of the authorities agree that these laws are rooted in the commandments that Moshe received at Sinai. However, they disagree over whether Moshe received the details related on the Plains of Moav at Sinai or whether he received the details on the Plains of Moav. However, it seems clear that Moshe did not teach these laws to the nation until they camped on the Plains of Moav poised to enter the Land of Israel.
These comments suggest an explanation for why this passage is repeated at the end of Sefer BeMidbar. The passage at the end of Sefer VaYikra asserts that no prophet can add commandments or alter those that were revealed at Sinai. However, the laws that were expounded by Moshe on the Plains of Moav were not revealed to the nation at Sinai. They were first explained to the nation on the Plains of Moav. Therefore, the Torah explains that also these laws are not subject to a prophet’s amendment or nullification.
In short, the message that emerges from these two passages is that the Torah is composed exclusively of the commandments that Moshe taught the nation – at Sinai or on the Plains of Moav. Hashem will not add to it or nullify any of its commandments. Any prophet claiming to have received a prophecy that alters the Torah is to be deemed an imposter and lair. This does not mean that the Sages are not entitled to interpret the Torah and to expound on its message. They have this authority. However, they must rely upon their own human knowledge and wisdom. They also have limited authority to create decrees, new institutions, and establish practices. But they may not claim that these new laws and practices are part of the Torah revealed at Sinai. They must identify these new laws as their own enactments and creations. They may not interpret the Torah or legislate on the basis of prophecy.
For the commandment that I command you today is not hidden from you and it is not distant from you. It is not in the heavens and not across the seas that you should say, “Who will cross the seas for us and take it for us and make it heard to us and we will perform it.” (Sefer Devarim 30:12-13)
2. The Torah does not reside in the heavens There is an additional passage in Sefer Devarim that is understood to communicate a similar message. Moshe exhorts Bnai Yisrael to observe the commandments. He tells them that the Torah is not in the heavens. The Sages of Talmud explain that the message of this passage is that questions of halachah cannot be decided by referring them to the heavens. We cannot resort to prophesy to resolve such question. Instead, we must rely upon our own wisdom and knowledge. In a famous discussion on the Talmud the Sages assert that even were we to receive an indication from the heavens – a miraculous wonder or a prophecy – regarding the proper solution to some halachic issue, the heavenly message is to be ignored and the issue must be decided on the basis of valid halachic debate and analysis.
This raises an interesting question. Apparently, the Talmud relies on two different passages for the identical message. The passages at the end of Sefer VaYikra and Sefer BeMidbar indicate that a prophecy cannot be used to amend or nullify any aspect of the Torah. This seems to be identical to the message of the passage from Sefer Devarim. Why are both sources required?
3. The two restrictions upon the prophet Rav Yitzchak Zev Soloveitchik discusses this issue and explains that the passages deal with very different issues. The passages ending Sefer VaYikra and Sefer BeMidbar communicate that prophecy cannot add or subtract from the Torah. No new commandment can be added and no existing commandment can be revoked. The passage in Sefer Devarim is dealing with a different issue. It is discussing the appropriateness of deciding an issue in halachah based upon Divine messages. In such an instance the prophet is not adding or subtracting to the commandments. The prophet is seeking to resolve a difficulty within the detailed laws of the commandment based upon heavenly intervention.
An example will help illustrate this distinction. If a prophet were to suggest that Hashem no longer wishes for us to observe the Shabbat or that Hashem has commanded us to observe Shabbat for an additional day of the week, then he would violate the prohibition of adding or subtracting from the Torah’s mitzvot. This is the prohibition associated with the passages at the end of Sefer VaYikra and Sefer BeMidbar. But what if the prophet merely claims that he received a prophecy regarding the number of meters in the Torah’s measurement of a cubit. He is not claiming to have received a new commandment or to have received a message cancelling a mitzvah. He is merely saying that he has received a communication from Hashem resolving an issue debated among the authorities. He has not violated the prohibition derived from the final passages of Sefer VaYikra and Sefer BeMidbar. However, he has suggested a resolution of a problem in halachah based upon heavenly communication. His ruling will be discounted because of the restriction in Sefer Devarim. The Sages are charged with the responsibility of resolving problems in halachah. We cannot resort to signs or other communications from heaven.
Rav Soloveitchik’s explanation is supported by Maimonides’ treatment of the issue. In the opening chapters of his code – the Mishne Torah – Maimonides explains that prophecy may not be used to add to or subtract from the commandments of the Torah. In order to fully appreciate Maimonides’ message it is helpful to consider its context. Maimonides begins the chapter by explaining that the Torah tells us that its commandments are permanent. They were reveled to Bnai Yisrael through Moshe for all generations. After stating this principle, Maimonides explains that any prophet attempting to alter the Torah is known to be false because he is contradicting the Torah itself – as revealed to us by Moshe. Maimonides then discusses other laws regarding the prophet. After that discussion he returns to the prophet’s role in establishing Torah laws and explains that the prophet cannot decide issues of halachah. It is interesting that Maimonides divides into two sections his discussion of the prophet’s exclusion from any role in establishing Torah laws. However, according to Rav Soloveitchik this is completely understandable. Maimonides is dealing with two separate and distinct issues. First, he deals with the issue of creating new laws or nullifying laws based upon prophecy. Such prophecies are dismissed based upon the passages at the end of Sefer VaYikra and Sefer BeMidbar. Only later does Maimonides discuss the issue of resorting to heavenly arbitrations regarding questions that arise within the laws of the mitzvot. Relying on heavenly communication for such issues is inappropriate based upon the passage in Sefer Devarim.
4. A confusing discussion in the Talmud and its resolution There is a mysterious discussion in Tractate Temurah regarding this issue. The Talmud explains that during the period that the nation mourned the death of Moshe 3,000 laws were forgotten. The nation turned to its new leader – Yehoshua – and asked him to restore the laws through prophecy. He responded that he could not do this and referred to the passage in Sefer Devarim. A latter generation appealed to the prophet Shmuel to restore these laws through prophecy and he refused. However, he based his response on the passages at the end of Sefer VaYikra and Sefer BeMidbar. Why did these two prophets refer to different passages in their responses?
Maharsha offers an interesting response to this question. He explains that Yehoshua and Shmuel were presented the same request. However, each faced different issues in determining their responses. Yehoshua had learned the entire Torah from Moshe. He had known all of its laws. However, he had forgotten a portion. The issue he faced was whether he could resort to prophecy in order to restore to himself information he had forgotten. If granted a response from Hashem, the prophecy would not be an addition to the Torah; it would be the restoration of the Torah that he had received from Moshe and forgotten. The passages at the end of Sefer VaYikra and Sefer BeMidbar were not relevant to this issue. Nonetheless, Yehoshua refused the request because of the passage in Sefer Devarim. Once given to Bnai Yisrael through Moshe, the Torah became our responsibility. The role of prophecy in halachah ended with Moshe.
When the same question was presented to Shmuel the situation had changed. Shmuel and his generation had not received the Torah from Moshe. The Torah they had received from their parents did not include the laws that were long ago lost. For Shmuel, these laws would be new and an addition to the Torah. Therefore, Shmuel responded that prophecy cannot add or subtract from the Torah and he referred to the passages ending Sefer VaYikra and BeMidbar.
 Mesechet Shabbat 104a.  Rav Meir Leibush ben Yechiel Michel (Malbim), HaTorah VeHaMitzvah – Commentary on Sefer BeMidbar 36:13.  Mesechet Baba Metzia 59b.  Whenever the Talmud refers to the passage, “These are the commandments” it does not complete the passage. Therefore, from the usage in the Talmud it is not clear whether the reference is to the passage in the end of Sefer VaYikra, the passage ending Sefer BeMidbar, or both. Torah Ohr cites Sefer VaYikra as the passage to which the Talmud refers. He may be relying on the position of Yonatan ben Uziel who clearly attributes the Talmud’s lesson to the passage ending Sefer VaYikra. Yonatan ben Uziel may be interpreting the Talmud in this manner in order to emphasize the relationship between the Talmud’s dictum and the Sinai Revelation. It is because the Torah was communicated to Moshe at Sinai through a Revelation in which the entire nation participated that the Torah is regarded as immutable. Any details added on the Plains of Moav or communicated to the nation at that time are regarded as on-par and indistinguishable from the Sinai Revelation. I will treat the Talmud’s reference as directed to both passages. But this is done for clarity and not as an objection to the conventional interpretation of the Talmud’s intention.  Rav Yitzchak Zev Soloveitchik, Chidushai HaGRIZ HaLeyve, Mesechet Temurah 16a.  Rabbaynu Moshe ben Maimon (Rambam / Maimonides) Mishne Torah, Hilchot Yesodai HaTorah, chapter 9.  Rav Soloveitchik notes that Maimonides never quotes the passages at the end of Sefer BeMidbar and Sefer VaYikra. In his discussion of both of the limitations upon prophecy he makes reference of the passage in Sefer Devarim. In other words, although Maimonindes identifies two separate issues, he relies on a single passage as the basis for both.  Mesechet Temurah 16a.  Rav Shmuel Eliezer Edels (Maharsha), Commentary on the Talmud, Mesechet Temurah 16a.