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: "And you shall be altogether joyful" — to include the nights of the last festival day in the obligation of rejoicing; or perhaps only the first festival day? The verse says "only"—it makes a distinction.
On the daf / in context: The final night of the festival is included in the obligation of simchah, whereas the first night is not.
Type of Learning
Derash on the verse (Sukkah) — the last night is included in simchah.
What Is Learned
The nights of the concluding festival day are included in the mitzvah of rejoicing; the first night is excluded.