The 119th mitzvah is that we1 are commanded to treat as holy the fruit which grows in the fourth year [from when the tree was planted, called neta revai].
The source of this commandment is G‑d's statement,2 "[And in the fourth year,] all its fruit shall be holy, and it shall be something for which G‑d is praised."
The law is that it must be brought to Jerusalem and eaten there by its owners, just like ma'aser sheni. The kohanim have no share in it, as the Sifri says: "The statement3 'The sacred offerings of each individual remain his own property, [and those which are given to the kohen become his]' gives all sanctified objects to the kohen except for the thanksgiving-offering, the peace-offering, the Pesach-offering, the ma'aser-offering, ma'aser sheni, and neta revai, which belong to the owner."
The details of this mitzvah are completely explained in the final chapter of tractate Ma'aser Sheni.
