Along with the Written Torah that was given to Moses at Mount Sinai, the Oral Torah, which includes the interpretations of the laws and inferences from the verses of the Written Torah, was also given.

“These are the statutes and ordinances and laws which the Lord gave between Him and the children of Israel at Mount Sinai by the hand of Moses” (Leviticus 26:46). “The statutes,” this is the Midrash; “ordinances,” these are the laws; “and laws,” this teaches that two Torahs were given to Israel, one written and one oral….

“At Mount Sinai by the hand of Moses.” This teaches that the entire Torah: its halakhot, inferences, and interpretation, were all given through Moses at Sinai.

“The Lord said to Moses: Ascend to Me, to the mountaintop, and be there; and I will give you the stone tablets and the law and the commandment that I have written, to teach them” (Exodus 24:12). Rabbi Levi bar Hama said that Rabbi Shimon ben Lakish said: What is the meaning of what is written: “And I will give you the stone tablets and the law and the commandment that I have written, to teach them”? “Tablets,” these are the Ten Commandments; “law,” these are the Five Books of Moses; “and the commandment,” this is the Mishna; “that I have written,” these are the Prophets and Writings; “to teach them,” this is the Talmud. This teaches that they were all given to Moses at Sinai.

“Because he scorned the word of the Lord” (Numbers 15:31); this is referring to one who says that the Torah did not originate from Heaven. And even if one said: The entire Torah is from Heaven except for this verse, and even if one said: The entire Torah originated from Heaven except for this inference by the Sages, or except for this a fortiori inference, or except for this verbal analogy, this is included in: “Because he scorned the word of the Lord.” (Sifra, Behukotai 26; Berakhot 5a; Sanhedrin 99a)