Deuteronomy 16:10 (KJV)

Six 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.

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

And 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 unto the Lord thy God, according as the Lord thy God hath blessed thee:

And 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 among you, in the place which the Lord thy God hath chosen to place his name there.

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