Leviticus 23:37-40

37These are the set feasts of Jehovah, which ye shall proclaim to be holy convocations, to offer an offering made by fire unto Jehovah, a burnt-offering, and a meal-offering, a sacrifice, and drink-offerings, each on its own day; 38besides the sabbaths of Jehovah, and besides your gifts, and besides all your vows, and besides all your freewill-offerings, which ye give unto Jehovah.

39Howbeit on the fifteenth day of the seventh month, when ye have gathered in the fruits of the land, ye shall keep the feast of Jehovah seven days: on the first day shall be a solemn rest, and on the eighth day shall be a solemn rest. 40And ye shall take you on the first day the fruit of goodly trees, branches of palm-trees, and boughs of thick trees, and willows of the brook; and ye shall rejoice before Jehovah your God seven days.