(Mishnah): If a person planted one species in his field, even he makes it into two threshing floors, he gives only one Peah for all of it.

If he planted two species, even if he made them into one threshing floor, he gives two Peahs.

If he planted two types of wheat in his field, if he made them into one threshing floor, he gives one Peah; if into two, he gives two Peahs.

Once, R. Shimon Ish HaMitzpeh planted before Rabban Gamliel and they went to the Lishkas HaGazis to ask them the law. Nachum the Scribe said - I have a tradition from R. Misha, who received it from Abba, who received it from the pairs (of Sages mentioned the first chapter of Pirkei Avos), who received it from the Prophets as an Oral tradition from Sinai - if he planted two types of wheat in his field, if he made them into one threshing floor, he gives one Peah; if into two, he gives two Peahs.

(Gemara): If he harvested half his white wheat and half his red wheat intending to make one threshing floor and he then decided to make two, he may not give Peah from the white for the red for any part of the crops, since ultimately they were separated.

If he harvested half the white and half the red wheat intending to make two threshing floors and he then decided to make one, he may give Peah from the white wheat at the end of the field for the red wheat there or from the white at the beginning of the field for the red there. He may give the white for the white if he has completed harvesting the field, but if not, he may not even give white for white.

If he harvested half of the white wheat and all of the red intending to make one threshing floor and he then decided to make two, when he finishes harvesting the white, he may give Peah from the second half of the white for the first half and also from the white for the red. (Even though he decided to make two threshing floors and separate the red and the white, that decision was made after the red was completely harvested and it does not take effect. See the commentary of Rav Chaim Kanievsky.)

(R. Zeira citing R. Yochanan): If a Halacha comes to your hand and you do not know its reason, do not reject it, as perhaps it is a Halacha L'Moshe MiSinai (an Oral tradition from Moshe at Mount Sinai) - as there are a number of such Halachos and they are embedded in Mishnah.

This is true - concerning our case of two types of wheat, if Nachum would not have explained it, would we have known that it is a Halacha L'Moshe MiSinai?

(R. Zeira citing R. Eliezer): The pasuk states (Hoshea 8:12), "I will write for you most {lit. the greater part} of my Torah"; is most of the Torah, the Written Torah? (Most of the Torah is the Oral Torah!) Rather, greater are the things that are learned through the 13 principles of expounding the Torah's text (of R. Yishmael) than the Halachos L'Moshe MiSinai (that cannot be sourced in the Torah).

Is that so? Rather, more cherished are those things that are expounded from the text than those expounded orally. (NOTE: Rav Chaim Kanievski changes the text here based on Yerushalmi Chagigah 1:8.)

(R. Yudah ben Pazi): "I will write for you most (the word 'Rav' literally means a quarrel/rebuke) of my Torah" - this refers to the admonitions; and the pasuk concludes, "like a foreign thing they are considered" - as they did not accept the rebuke.

(R. Avin): If I would have written down for you most of my Torah (meaning the Oral Torah), you would have been considered a foreign nation like all of the other nations as they would have also had access to all of the Torah.

(R. Chagai citing R. Shmuel bar Nachman): Some things were given orally and some were given in writing; and we would not know which of them are more cherished; when the pasuk states (Shemos 34:27), "...as according to {lit. upon the mouth of} these words I have made a covenant with you and with Yisrael" - this shows that the Oral law is more cherished.

There is a dispute between R. Yochanan and R. Yudan bei R. Shimon - one said - if you keep that which is oral and that which is written, I have a covenant with you; if not, I do not.

The other one said - if you keep that which is oral and fulfil that which is written, you receive reward; if not, you do not.

(R. Yehoshua ben Levi): (The pasuk states (Devarim 9:10), "And Hash-m gave me two stone tablets, inscribed by the finger of God, and on them was [inscribed] according to all the words that Hash-m spoke with you on the mountain..."). The pasuk could have said 'on them' and it said 'and on them'; it could have said 'all' and it said 'according to all'; it could have said 'words' and it said 'the words' - these extra letters teach that what was given to Moshe at Sinai was pesukim, Mishnah, Talmud, Aggadah and even that which an experienced student would ask his Rav in the future.

From where is this learned? The pasuk states (Koheles 1:10), "There is a thing of which (someone) will say, 'See this, it is new.' It has always been..."

(R. Zeira citing Shmuel): We cannot derive laws from Halacha L'Moshe MiSinai, nor from Midrashim, nor from Toseftos - only from Talmud (the words of the Amoraim).

Question from Baraisa (R. Chalafta ben Shaul): The case of the two types of wheat also applies to two types of barley. (This is deriving a law from Halacha L'Moshe MiSinai?!)

Answer (R. Zeira): Barley was also part of the Halachah L'Moshe MiSinai but was forgotten.

Question: How could barley be like wheat - doesn't a later Mishnah say - if one divides up moist onions to sell in the market, leaving the dry onions for himself, it is like the law of the threshing floor and they are considered two types and he must give Peah on them separately. Perhaps you could say that barley is included in the term 'threshing floor', but could you say that about onions? Rather, it must be that Chazal did derive from Halacha L'Moshe MiSinai...?

Answer: That was also part of the tradition but it was forgotten.

(R. Chananya citing Shmuel): One may not derive from a Rabbi's Halachic ruling (as perhaps there were additional unspoken reasons for his ruling).

(R. Mana): This applies to a student who doesn't have sufficient understanding, but if he is himself a Torah scholar who fully understands the logic of the ruling, he may apply it.

(R. Chananya citing Shmuel responds): Even if he is himself a Torah scholar, he may not apply it if it is a ruling that involves a dispute between the Sages, but if it does not, even if the student is not a Torah scholar, he may apply it.