Deuteronomy 16:7-17

7And thou shalt roast and eat it in the place which the LORD thy God shall choose: and thou shalt turn in the morning, and go unto thy tents.

8Six days thou shalt eat unleavened bread: and on the seventh day shall be a solemn assembly to the LORD thy God; thou shalt do no work therein.

9Seven weeks shalt thou number unto thee: from the time thou beginnest to put the sickle to the standing corn shalt thou begin to number seven weeks.

10And thou shalt keep the feast of weeks unto the LORD thy God with a tribute of a freewill offering of thine hand, which thou shalt give, according as the LORD thy God blesseth thee:

11and thou shalt rejoice before the LORD thy God, thou, and thy son, and thy daughter, and thy manservant, and thy maidservant, and the Levite that is within thy gates, and the stranger, and the fatherless, and the widow, that are in the midst of thee, in the place which the LORD thy God shall choose to cause his name to dwell there.

12And thou shalt remember that thou wast a bondman in Egypt: and thou shalt observe and do these statutes.

13Thou shalt keep the feast of tabernacles seven days, after that thou hast gathered in from thy threshing-floor and from thy winepress:

14and thou shalt rejoice in thy feast, thou, and thy son, and thy daughter, and thy manservant, and thy maidservant, and the Levite, and the stranger, and the fatherless, and the widow, that are within thy gates.

15Seven days shalt thou keep a feast unto the LORD thy God in the place which the LORD shall choose: because the LORD thy God shall bless thee in all thine increase, and in all the work of thine hands, and thou shalt be altogether joyful.

16Three times in a year shall all thy males appear before the LORD thy God in the place which he shall choose; in the feast of unleavened bread, and in the feast of weeks, and in the feast of tabernacles: and they shall not appear before the LORD empty:

17every man shall give as he is able, according to the blessing of the LORD thy God which he hath given thee.