Leviticus 23:40-41

⁴⁰You shall take on the first day the fruit of majestic trees, branches of palm trees, and boughs of thick trees, and willows of the brook; and you shall rejoice before the LORD your God seven days.

⁴¹You shall keep it as a feast to the LORD seven days in the year. It is a statute forever throughout your generations. You shall keep it in the seventh month.