Deuteronomy 16:9-11

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.