Exodus

Three 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:

And the feast of harvest, the firstfruits of thy labours, which thou hast sown in the field: and the feast of ingathering, which is in the end of the year, when thou hast gathered in thy labours out of the field.

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.

Also in the day of the firstfruits, when ye bring a new meat offering unto the Lord, after your weeks be out, ye shall have an holy convocation; ye shall do no servile work:

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: