Leviticus 23:41 in the King James Version
And ye shall keep it a feast unto the LORD seven days in the year. It shall be a statute for ever in your generations: ye shall celebrate it in the seventh month.
Context
40 You 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.
41 You 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.
42 You shall dwell in temporary shelters for seven days. All who are native-born in Israel shall dwell in temporary shelters,