Maasrot, Chapter Five, Mishnah Five
In rabbinic language Syria refers to the land that borders Israel to the north and east but is not considered fully part of Israel. The rules of tithing and terumah do apply to produce grown by a Jew in Syria but one who purchases produce in Syria can assume that it grew on gentile land and is therefore exempt from the laws of tithing and terumah. Our mishnah deals with a person who is buying land in Syria from a Gentile, and the land has produce growing on it that is in various stages of growth.
1) One who buys a field of vegetables in Syria:
a) If before the season for tithing arrived, then he is liable to tithe.
b) If after the season for tithing he is exempt, and he may go on gathering in his usual manner. Rabbi Judah says: he may even hire workers and gather.
2) Rabban Shimon ben Gamaliel says: When does this apply? If he has bought the land. But if, he has not bought the land, even before the season for tithing arrived he is exempt.
3) Rabbi [Judah Hanasi] says: he must also tithe according to calculation.
Section one: If he buys a field from a Gentile before the season for tithing the vegetables in the field has arrived, then he is liable to tithe because the vegetables became liable for tithes under his (Jewish) ownership. However, if he buys the field after the season for tithing has already arrived, he need not tithe the vegetables. Furthermore, even if the vegetables continue to grow after this time, he may still collect them and eat without tithing.
In contrast, in the land of Israel when one buys a field from a non-Jew he always must tithe the produce, no matter when he buys it.
Section two: Rabbi Judah adds that he may even hire workers to help him collect the added growth from the produce, even though this will cause more people to know that he is not tithing this field.
Section three: Rabban Shimon ben Gamaliel says that he is liable to tithe the produce in this field only if he bought the land. If he didnt buy the land, but was only renting the land, then the produce is always exempt from tithes.
Section four: Rabbi holds that when he is exempt from tithing, he is still liable to tithe on the percentage of growth that the vegetable experienced after he bought it. Thus if he buys the field after the season for tithing has arrived, he is exempt from tithing on the growth that occurred before this season, but he is liable to tithe for the percentage of growth that took place after he bought the field.