Midrasch zu Dewarim 16:13

3) "the festival of Succoth, seven days to the L–rd": I might think that the chagigah (the festival offering) and the succah should be for the L–rd; it is, therefore, written (Devarim 16:13) "The festival of Succoth should you make for yourselves seven days." If (only) the latter (were written), I would think that both the chagigah and the succah reverted to the man; it is, therefore, written "the festival of Succoth, seven days to the L–rd." How is this to be reconciled? The chagigah, to the L–rd; the succah, to the man.

7) I might think, when all the fruits are gathered. It is, therefore, written (Devarim 16:13) "from your threshing floor and from your winepress." "From your threshing floor," and not all of your threshing floor; "from your winepress," and not all of your winepress. If "from your threshing floor and from your winepress, I would think (even the lesser) part of them; it is, therefore, written "when you gather the produce of the land." How so? Exert yourselves to intercalate the year in such a manner that the festival falls out with most of the gathering of all of the fruits.

(Devarim 16:13) "The festival of Succoth shall you make for yourself, seven days": Why is this stated? Because it is written (Vayikra 23:34) "the festival of Succoth, seven days, for the Most High," I might think (that it is being made for the L-rd); it is, therefore, written "shall you make for yourself."