The Sages taught: There was an incident involving one gentile who came before Shammai. The gentile said to Shammai: How many Torahs do you have? He said to him: Two, the Written Torah and the Oral Torah. The gentile said to him: With regard to the Written Torah, I believe you, but with regard to the Oral Torah, I do not believe you. Convert me on condition that you will teach me only the Written Torah. Shammai scolded him and cast him out with reprimand. The same gentile came before Hillel, who converted him and began teaching him Torah. On the first day, he showed him the letters of the alphabet and said to him: Alef, bet, gimmel, dalet. The next day he reversed the order of the letters and told him that an alef is a tav and so on. The convert said to him: But yesterday you did not tell me that. Hillel said to him: You see that it is impossible to learn what is written without relying on an oral tradition. Didn’t you rely on me? Therefore, you should also rely on me with regard to the matter of the Oral Torah, and accept the interpretations that it contains.

(17) It is a law for all time throughout the ages, in all your settlements: you must not eat any fat or any blood.

...You shall not boil a kid in its mother’s milk.

(40) On the first day you shall take the product of hadar trees...and you shall rejoice before the ETERNAL your God seven days.

(21) If the place where GOD has chosen to establish the divine name is too far from you, you may slaughter any of the cattle or sheep that GOD gives you, as I have instructed you; and you may eat to your heart’s content in your settlements.

וזבחת … כאשר צויתך THEN THOU MAYEST SLAUGHTER … AS I HAVE COMMANDED THEE — This teaches us that there was already a commandment regarding the slaughtering of animals — as to how one should slaughter; it is not written in the Torah but it comprises the traditional regulations regarding the slaughter of animals that were given orally (נאמרו) to Moses on Mount Sinai (Sifrei Devarim 75:7; Chullin 28a).

(1) The daughters of Zelophehad, of Manassite family—son of Hepher son of Gilead son of Machir son of Manasseh son of Joseph—came forward. The names of the daughters were Mahlah, Noah, Hoglah, Milcah, and Tirzah. (2) They stood before Moses, Eleazar the priest, the chieftains, and the whole assembly, at the entrance of the Tent of Meeting, and they said, (3) “Our father died in the wilderness. He was not one of the faction, Korah’s faction, that banded together against GOD, but died for his own sin; and he has left no sons. (4) Let not our father’s name be lost to his clan just because he had no son! Give us a holding among our father’s kinsmen!” (5) Moses brought their case before GOD.

This is why the Rabbis say, God made a covenant with Israel only for the sake of the oral law. This is because the written law can not be understood except with the oral law

Matters transmitted orally are the explanation for matters that are written. When they are only transmitted orally, it is impossible to understand them except from a teacher, who will explain it to him well, whereas if the [oral material] were written down, one might be in doubt about it, and not understand the language

(12) GOD said to Moses, “Come up to Me on the mountain and wait there, and I will give you the stone tablets with the teachings and commandments that I have inscribed to instruct them.”

And Rabbi Levi bar Ḥama said that Rabbi Shimon ben Lakish said: God said to Moses, “Ascend to Me on the mountain and be there, and I will give you the stone tablets and the Torah and the mitzva that I have written that you may teach them” (Exodus 24:12), meaning that God revealed to Moses not only the Written Torah, but all of Torah, as it would be transmitted through the generations. The “tablets” are the ten commandments that were written on the tablets of the Covenant, the “Torah” is the five books of Moses.The “mitzva” is the Mishna, which includes explanations for the mitzvot and how they are to be performed.
“That I have written” refers to the Prophets and Writings, written with divine inspiration. “That you may teach them” refers to the Talmud, which explains the Mishna. These explanations are the foundation for the rulings of practical halakha. This verse teaches that all aspects of Torah were given to Moses from Sinai.

The Sages taught the following baraita: What was the order of teaching the Oral Law? How was the Oral Law first taught? Moses learned directly from the mouth of the Almighty. Aaron entered and sat before him, and Moses taught him his lesson as he had learned it from God. Aaron moved aside and sat to the left of Moses. Aaron’s sons entered, and Moses taught them their lesson while Aaron listened. Aaron’s sons moved aside; Elazar sat to the right of Moses and Itamar sat to the left of Aaron. Rabbi Yehuda disagreed with the first tanna with regard to the seating arrangements and said: Actually, Aaron would return to sit to the right of Moses. The elders entered and Moses taught them their lesson. The elders moved aside, and the entire nation entered and Moses taught them their lesson. Therefore, Aaron had heard the lesson four times, his sons heard it three times, the elders heard it twice, and the entire nation heard it once.Moses then departed to his tent, and Aaron taught the others his lesson as he had learned it from Moses. Aaron then departed and his sons taught the others their lesson. His sons then departed and the elders taught the rest of the people their lesson. Hence everyone, Aaron, his sons, the elders and all the people, heard the lesson taught by God four times.

(1) Moses received the Torah at Sinai and transmitted it to Joshua, Joshua to the elders, and the elders to the prophets, and the prophets to the Men of the Great Assembly...

And when he died, peace be upon him – since he bequeathed to Yehoshua that which was imbued to him of the explanation – Yehoshua and the people of his generation applied their wisdom and their thought to [the received Torah]. And everything that he received from Moshe – he or any of the elders – there is nothing to say about it; and no disagreement arose about it. And whoever did not hear an explanation from the mouth of the prophet, peace be upon him, about matters that derive from them, extrapolated laws by propositions from the thirteen [exegetical] principles through which the Torah is expounded, which were given at Mount Sinai. And among those laws that they derived, there are some things wherein no disagreement arose, but [rather] they agreed about them. And there were among them [those] wherein disagreements between two opinions did arise – this one says like this, and that one says like that; this one reasons according to his reasoning and becomes more sure of his opinion, and that one reasons according to his reasoning and becomes more sure of his opinion; as principles of analysis that are by way of argumentation will result in such a result. And when a disagreement would arise, they would go according to the majority, as it states (Exodus 23:2), "you will incline after the majority."

Furthermore, because it would be impossible for God’s Torah to be complete in such a way that it would suffice for all times, because there are always new details in human affairs in laws, and the situations that could occur are far too many to include in a book. Therefore, Moshe was given orally on Sinai general methods, which are hinted at concisely in the written text, so that that through them the sages in every generation could extract new details.

Rabbi Yoḥanan said: Those who write halakhot are considered like those who burn the Torah, and one who learns from written halakhot does not receive the reward of studying Torah. Evidently, it is prohibited to send halakhot in letters. Before resolving the difficulty, the Gemara further discusses the prohibition of writing down the Torah: Rabbi Yehuda bar Naḥmani, the disseminator for Reish Lakish, expounded as follows: One verse says: “Write you these words,” and one verse says, i.e., it states later in that same verse: “For by the mouth of these words” (Exodus 34:27). These phrases serve to say to you: Words that were taught orally you may not recite in writing, and words that are written you may not recite orally, i.e., by heart. And furthermore, the school of Rabbi Yishmael taught: The word “these” in the command “write you these words” serves to emphasize that these words, i.e., those recorded in the Written Law, you may write, but you may not write halakhot, i.e., the mishnayot and the rest of the Oral Law.

It is taught in a baraita that Rabbi Yosei said: Initially, discord would not proliferate among Israel...From the time that the disciples of Shammai and Hillel grew in number, and they were disciples who did not attend to their masters to the requisite degree, dispute proliferated among the Jewish people and the Torah became like two Torahs.

Since from the time of the disciples of Shammai and Hillel, three generations before him [meaning Rebbi], there were great disputes regarding the meanings of the Torah and there arose the possibility of there being two Torahs amongst Israel, due to the oppression of the kingdom [Rome] and the evil decrees passed against Israel. Because of these [troubles] they [the scholars of Israel] were unable to clarify the differing opinions and settle them, until [came] the time of Rebbi. Then did the Lord give favor unto Rebbi in the eyes of the Roman emperor, Antonius, and the troubles subsided, and Rebbi was able to gather all of the scholars of the Land of Israel to him [in Beit She’arim and Tzippori]. Until his [Rebbi's] days, there were no ordered tractates [of the Oral Law] but rather every student studied and reviewed lectures that he heard from the great men and he ascribed to them these teaching s-"this halachah heard from this and this scholar." Now, when they all gathered together [at Rebbi's yeshivah], each of the scholars repeated what he had learned and together they worked to clarify the reasons behind disparate opinions and they settled as to which opinion was to be deemed correct. And then they ordered these opinions and decisions into tractates: the laws of torts by themselves, the laws of levirate marriages by themselves, the laws of the Temple service by themselves, [etc]...

Rabbenu Hakadosh composed the Mishnah. From the days of Moses, our teacher, until Rabbenu Hakadosh, no one had composed a text for the purpose of teaching the Oral Law in public. Instead, in each generation, the head of the court or the prophet of that generation would take notes of the teachings which he received from his masters for himself, and teach them verbally in public. Similarly, according to his own potential, each individual would write notes for himself of what he heard regarding the explanation of the Torah, its laws, and the new concepts that were deduced in each generation concerning laws that were not communicated by the oral tradition, but rather deduced using one of the thirteen principles of Biblical exegesis and accepted by the high court. This situation continued until [the age of] Rabbenu Hakadosh. He collected all the teachings, all the laws, and all the explanations and commentaries that were heard from Moses, our teacher, and which were taught by the courts in each generation concerning the entire Torah. From all these, he composed the text of the Mishnah. He taught it to the Sages in public and revealed it to the Jewish people, who all wrote it down. They spread it in all places so that the Oral Law would not be forgotten by the Jewish people. Why did Rabbenu Hakadosh make [such an innovation] instead of perpetuating the status quo? Because he saw the students becoming fewer, new difficulties constantly arising, the Roman Empire spreading itself throughout the world and becoming more powerful, and the Jewish people wandering and becoming dispersed to the far ends of the world. [Therefore,] he composed a single text that would be available to everyone, so that it could be studied quickly and would not be forgotten. Throughout his entire life, he and his court taught the Mishnah to the masses.

(126) It is a time to act for GOD, for they have violated Your teaching.

And the verse states: “It is time to work for the Lord; they have made void Your Torah” (Psalms 119:126). Of this, Rava said: This verse can be interpreted from beginning to end, and can be interpreted from end to beginning.The Gemara elaborates: This verse can be interpreted from beginning to end: It is time to work for the Lord; what is the reason? Because they have made void Your Torah, so it must be remedied.

Those who do His will have violated His Torah, for example, Eliyahu on Mount Carmel (Melachim I, 18:7), who offered sacrifices on a high place [an altar outside the Temple], at a time when that was forbidden, in order to create a protection and boundary for the Jewish people, for the sake of the Holy One, blessed be He.

One proof for this suggestion is that Rabbi Yoḥanan and Reish Lakish would read from a scroll of aggada, containing the words of the Sages, on Shabbat. And they did so because they taught as follows: Since one cannot remember the Oral Law without writing it down, it is permitted to violate the halakha, as derived from the verse: “It is time to work for the Lord; they have made void your Torah” (Psalms 119:126). They said it is better to uproot a single halakha of the Torah, i.e., the prohibition of writing down the Oral Torah, and thereby ensure that the Torah is not forgotten from the Jewish people entirely.

...Just like a doctor may amputate a person's hand or foot so that the person as a whole will live; so, too, at times, the court may rule to temporarily violate some of the commandments so that they will later keep all of them. In this vein, the Sages of the previous generations said: "Desecrate one Sabbath for a person's sake so that he will keep many Sabbaths."

Rav composed the Sifra and the Sifre to explain the sources for the Mishnah. Rabbi Chiyya composed the Tosefta to explain the subjects [discussed in] the Mishnah. Rabbi Hoshaia and bar Kafra composed baraitot to explain the matters [discussed in] the Mishnah...The Sages of the Mishnah also composed other texts to explain the words of the Torah. Rabbi Hoshaia, the disciple of Rabbenu Hakadosh, composed an explanation of the book of Genesis. Rabbi Yishmael [composed] an explanation beginning at "These are the names" [the beginning of the book of Exodus,] until the conclusion of the Torah. This is called the Mechilta. Rabbi Akiva also composed a Mechilta. Other Sages of the following generations composed other [collections of the] interpretations [of verses] (Medrashim)...

(29) Behold, My word is like fire—declares GOD—and like a hammer that shatters rock!

The house of Rabbi Yishmael taught: “like a hammer shatters a rock.” Just as a hammer splits [the rock] into myriad shards, so too, a single verse can be explained in many ways.

For the Torah She-be’al Peh is compared to all [types of] drink, as they said (Ta’anit 7a) that “the words of Torah are compared to water, wine, and milk.” And this is Torah She-be’al Peh, for regarding this was it said (Yeshaya 55:1) “Oh all who thirst [go to the water],” which is expounded to refer to Talmud. And this is Torah She-be’al Peh, for Torah She-bichtav is rolled up and settled as they [the sages] say in Kiddushin (66a)…And what they [the sages] said (Ta’anit 9a) “The well [in the wilderness] was by merit of Miryam,” that the well had the flavor of all drinks, as they said in Mechilta (Yitro 1), like the manna which had the taste of all the foods as they said in Yoma (75a). And this hints at Torah She-be’al Peh.