On the
fifteenth day of the seventh month, when you gather in the fruit of the
land, observe the festival of יהוה for seven days. On the first day is a
rest, and on the eighth day a rest. And you shall take for yourselves
on the first day the fruit of good trees, branches of palm trees, twigs
of leafy trees, and willows of the stream, and shall rejoice before יהוה
your Elohim for seven days.
Lev 23:39 -40