Albert Barnes Commentary Deuteronomy 16:9-12

"Seven weeks shalt thou number unto thee: from the time thou beginnest to put the sickle to the standing grain shalt thou begin to number seven weeks. And thou shalt keep the feast of weeks unto Jehovah thy God with a tribute of a freewill-offering of thy hand, which thou shalt give, according as Jehovah thy God blesseth thee: and thou shalt rejoice before Jehovah thy God, thou, and thy son, and thy daughter, and thy man-servant, and thy maid-servant, and the Levite that is within thy gates, and the sojourner, and the fatherless, and the widow, that are in the midst of thee, in the place which Jehovah thy God shall choose, to cause his name to dwell there. And thou shalt remember that thou wast a bondman in Egypt: and thou shalt observe and do these statutes." — Deuteronomy 16:9-12 (ASV)

Feast of Weeks; and (Deuteronomy 16:13–17), Feast of Tabernacles. Nothing is here added to the rules given in Leviticus and Numbers except the clauses so often recurring in Deuteronomy and so characteristic of it, which restrict the public celebration of the festivals to the sanctuary, and enjoin that the enjoyments of them should be extended to the Levites, widows, orphans, etc.