Deuteronomy 16:9-12

9Seven weeks shalt thou number unto thee: begin to number the seven weeks from such time as thou beginnest to put the sickle to the grain. 10And thou shalt keep the feast of weeks unto Yhwh thy God with a tribute of a freewill offering of thine hand, which thou shalt give unto the Lord thy God, according as Yhwh thy God hath blessed thee:1 11And thou shalt rejoice before Yhwh 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 among you, in the place which Yhwh thy God hath chosen to place his name there. 12And thou shalt remember that thou wast a bondman in Egypt: and thou shalt observe and do these statutes.