Seven days you shall keep a festival to Hashem your God in the place that Hashem will choose, for Hashem your God will bless you in all your produce and in all the work of your hands, and you shall be altogether joyful.
English: "Seven days you shall keep a festival" — It was taught: Rabbi Shimon says: Pesach and the [Sukkos] festival, which are not seasons of labor, the Torah said to observe for seven and eight days respectively; Atzeres, which is a season of labor, is only one day—this teaches that the Torah is concerned for the property of Israel.
On the daf / in context: The shorter duration of Shavuos reflects the Torah’s consideration for the agricultural work of the season.
Type of Learning
Derash on the verse (Sifrei) — the Torah spares Israel’s property.
What Is Learned
Shavuos is limited to a single day because it falls in the busy agricultural season; the Torah is concerned not to impose excessive loss of labor.