The Talmud questions the necessity of a verse to teach the law of Tosfos Shevuos, if there already exists an Halacha that allows plowing for young trees, implying that a prohibition exists otherwise.
Does the existence of an Halacha treating a Mitzva negate the necessity for a source? For example, do the Halachos of Tefillin render all the verses concerning Tefillin unnecessary? What does the Talmud mean by this?
Dov Frank, Brooklyn, NY, U.S.A.
The Gemara here refers to a special kind of Halachah - a "Halachah l'Moshe mi'Sinai" i.e. a Halachah that Moshe Rabeinu received directly on Mount Sinai. This means that some of the Halachos of the Torah are stated in the written Torah that we received on Sinai whilst others were said by Hash-m to Moshe but not written down. However both types are Deoraisa, and have a greater authority than Takanos etc. that the Rabbis instituted later on.
Therefore the Gemara (end 3b) asks how can one say that the prohibition against plowing at the end of the 6th year is a "Hilchesah" - i.e. a Halachah said to Moshe on Sinai but not written down - surely this prohibition is actually written in the Torah, in the word "u'b'Chorish" from which Rabbi Akiva learns that plowing at the end of the 6th year is also forbidden Mideoraisa?!
The analogy to Tefilin would be, for instance, what the Gemara says in Menachos 35a that there is a haalachah l'Moshe mi'Sinai that the boxes of the Tefilin must be square. There is no verse which says that they must be square but this Halachah was said directly orally to Moshe on Har Sinai and is a Deoraisa Halachah.
Of course a Halachah stated explicitly in the Torah is also a Halachah and the Gemara always tries to find the source in the Torah for every Halacha but the word "Hilchesah" here refers specifically to Halachah l'Moshe mi'Sinai.
Best Wishes,
D. Bloom