Leviticus 23:37-40

37These are the feasts of the Lord, which ye shall proclaim to be holy convocations, to offer an offering made by fire unto the Lord, a burnt offering, and a meat offering, a sacrifice, and drink offerings, every thing upon his day:

38Beside the sabbaths of the Lord, and beside your gifts, and beside all your vows, and beside all your freewill offerings, which ye give unto the Lord.

39Also in the fifteenth day of the seventh month, when ye have gathered in the fruit of the land, ye shall keep a feast unto the Lord seven days: on the first day shall be a sabbath, and on the eighth day shall be a sabbath.

40And ye shall take you on the first day the boughs of goodly trees, branches of palm trees, and the boughs of thick trees, and willows of the brook; and ye shall rejoice before the Lord your God seven days.1