Mishnah 9 in chapter 3 of Maseches Terumos deals with a fascinating question: Terumah that was separated by non-Jews. At the beginning of the tractate we learned that a non-Jew cannot separate Terumah, but there the case was a non-Jew separating Terumah from a Jew's produce. Our Mishnah discusses a different case: a non-Jew owns his own field in Eretz Yisrael, he grows his wheat in it, and he wishes to separate Terumah from it and give it to a kohen. He wants to do the right thing, to fulfill a mitzvah. Does his declaration take effect? Does the separation work?
The View of the Tanna Kamma:
Our Mishnah, according to the Tanna Kamma, rules that the separation is effective. There is a broad halachic issue at stake here regarding how we view land held by a non-Jew in Eretz Yisrael, and whether his acquisition removes it from the obligation of tithes. The Tanna Kamma holds that a non-Jew's acquisition in Eretz Yisrael remains obligated in tithes, and therefore when he separates and designates it as Terumah, the designation takes effect and is binding.
The Reward of the Non-Jew Who Separates:
Not only that, but the Rambam writes in his Commentary on the Mishnah, and expands on it in the Yad HaChazakah at the end of Hilchos Melachim, that a non-Jew who does this receives reward for his deed. He fulfills a mitzvah by giving the Terumah, even though he is not commanded in it: a non-Jew is commanded in seven mitzvos only - seven categories of mitzvos incumbent upon the descendants of Noach - and giving Terumah is not among them. Even so, if he did it, he receives reward for it in the World to Come, provided the other necessary conditions are met. However, his reward is the reward of one who is "not commanded and does," and therefore it is less than the reward of one who is commanded and does.
So it is with every good deed performed without a command: the reward of the one who does it is less than the reward of one who was commanded in the matter. For example, women are exempt from taking the lulav on Sukkos - one of eight positive time-bound mitzvos from which women are exempt. A woman who takes a lulav receives reward, but not like the reward of a man, since she is not commanded and does. Her act is an act of merit, but its merit is lesser. The reason for this lies beyond the scope of our present discussion.
Who Are the Kusim:
The Mishnah says "the non-Jew and the Kusi." The Kusim are the Samaritans, who were brought from Kusa after the Assyrians exiled the ten tribes from the north of Eretz Yisrael and replaced the population. Their status was in doubt - Jews or non-Jews - because after they were attacked by lions they concluded that the local god was not pleased with their conduct, and they converted. Hence the question that runs through the Mishnayos: was this a legitimate conversion, or was it a "conversion of lions" - a conversion inspired by the lions and not by the Holy One, Blessed is He. And indeed the Tannaim disagreed about this.
After the sealing of the Mishnah it was discovered that the Kusim had set up an idol in the form of a dove on Mount Gerizim, and from then on it was ruled that their status is that of full non-Jews. In the time of the Mishnah this was not clear, and our Mishnah groups the Kusi together with the non-Jew - from which it appears that it treats them as non-Jews.
The Language of the Mishnah:
"Terumasan Terumah" - what they separated as Terumah receives the status of Terumah, and therefore a non-kohen may not eat it, and according to the Tanna Kamma this is on a Torah level.
"U'ma'asroseihen ma'aser" - the tithe they separated for the Levi also takes effect and is binding.
"V'hekdeishan hekdesh" - if they consecrated an animal as an olah, the consecration takes effect just as with a Jew.
And the reason is: we find sources that allow a non-Jew to consecrate an animal as an olah offering, and he indeed brings it and it is offered on the altar. Since he has the power to create an olah offering, he also has the power to create Terumah and ma'aser.
The laws of Terumah separated by a non-Jew:
Since according to the first Tanna this is full Terumah by Torah law, it renders a mixture medumah - meaning, if it fell into unconsecrated produce, the mixture is not judged by the ordinary rules of majority; rather, when like falls into like, one hundred times the amount of permitted produce is required (more than ninety nine parts) in order to nullify the portion of Terumah that fell in.
And further: "vechayav aleha chomesh" - one is liable for an added fifth on account of it. A non-kohen who ate Terumah unintentionally is like an unintentional thief, and he must return what he took - if he ate four grapes of Terumah, he must return four grapes to the kohen. Beyond that, an additional payment is imposed on him, something like a fine: an extra fifth grape, which is the chomesh, as part of the process of atonement. Since the Terumah separated by the non-Jew is full Terumah, the non-kohen who ate it returns not only what he ate but also the added fifth - a fifth grape for every four that he ate.
"veRabbi Shimon poter" - and Rabbi Shimon exempts. Rabbi Shimon disagrees and holds that there is no obligation of the added fifth, because in his view the Terumah of a non-Jew is not genuine Terumah but only Terumah by rabbinic law: the Sages gave it the status of Terumah, but it does not carry the power to generate obligations such as the added fifth. In practice, the halachah follows the first Tanna, and the Terumah of a non-Jew is Terumah.
The fourth year vineyard of a non-Jew:
Let us return to the words of the Mishnah that we skipped over: "Rabbi Yehudah omer, ein lanochri kerem revai, vachachamim omrim yesh lo" - Rabbi Yehudah says, a non-Jew has no fourth year vineyard, and the Sages say he does. "Revai" means fourth, and the Tannaim disagree throughout the Mishnah as to whether the law of fourth year fruit applies to all trees or only to the produce of a vineyard. Our Mishnah uses the phrase "kerem revai," a fourth year vineyard, so we will discuss grapevines and assume that this is the scope of the law, even though in practice we treat the obligation of the fourth year as applying to all fruit trees.
Here is the background: during the first three years of a fruit tree or a grapevine, all of their fruit is absolutely forbidden, and it is called orlah - the same word used for the foreskin removed at a bris milah. The fruit is set aside, pushed off to the side, and is not available for eating. In the fourth year the status of orlah lapses and the fruit is permitted, but with limitations: this is revai, and its law is like that of Maaser Sheni - one brings it up to Jerusalem or redeems it onto a coin, and it is eaten specifically there, in a state of purity.
The question in our Mishnah is whether a non-Jew who owns a vineyard, are his grapes in the fourth year subject to the law of revai or not. The commentators disagree as to whether this refers only to the Land of Israel or even to outside the Land - and it is worth noting that the obligations of orlah apply even outside the Land of Israel, though their application differs somewhat.
Rabbi Yehudah holds that there is no law of revai in the vineyard of a non-Jew, and the Sages disagree and hold that there is. From other sources, including the Tosefta, it emerges that Rabbi Yehudah is speaking specifically about outside the Land - and in light of that this is striking, since according to the Sages, even outside the Land all of these restrictions apply to the fourth year fruit of a non-Jew, at least in a vineyard. And the halachah follows the Sages: the law of revai applies to fourth year fruit, even if it was grown by a non-Jew. This has far reaching implications for the food we eat and for the manner in which it is eaten in the Land of Israel to this very day.
In summary: we learned that according to the first Tanna, which is the halachah in practice, the Terumah of a non-Jew or of a Kuti is Terumah, their tithes are tithes and their consecrations are consecrated - and the reason is that they have the ability to consecrate an animal as an olah offering. This Terumah renders a mixture medumah and carries the obligation of the added fifth, unlike the view of Rabbi Shimon, who holds that it is only rabbinic. We discussed the reward of a non-Jew who fulfills a mitzvah as one who "is not commanded and yet does," the uncertain status of the Kutim, and the dispute between Rabbi Yehudah and the Sages regarding the fourth year vineyard of a non-Jew, where the halachah follows the Sages.