Shevi'is, Chapter 6, Mishnah 2. This mishnah discusses the status of the region called Surya (the source of the name Syria) during the Shemittah year.
The unique status of Surya:
Surya was conquered by King David, but since it was conquered before he had conquered all of Eretz Yisrael, it never received the full sanctity of Eretz Yisrael and never had the full status of Eretz Yisrael. Therefore, in certain matters the laws of Eretz Yisrael apply there, and in other matters they do not.
Accordingly the mishnah says: "Osin b'talush b'Surya, aval lo bemechubar" - in Surya it is permitted during the Shemittah year to perform work on produce that is not attached to the ground, but work on produce that is attached to the ground is forbidden.
The mishnah then lists those activities. The permitted activities:
"Dashin" - threshing.
"V'zorin" - winnowing.
"V'dorchin" - treading the grapes.
"U'me'amrin" - gathering the sheaves of wheat, and so on.
And in contrast, the forbidden activities:
"Aval lo kotzrin" - one does not harvest the grain that has grown.
"V'lo botzrin" - harvesting is done with grain, while betzirah is the picking of grapes.
"V'lo moskin" - one does not pick the olives.
Rabbi Akiva's rule:
Rabbi Akiva gives a rule: "Kol shekayotzei bo mutar b'Eretz Yisrael, osin oso b'Surya" - anything that is permitted on Shemittah in Eretz Yisrael by Torah law, such as work on produce that is not attached to the ground, is forbidden in Eretz Yisrael only by rabbinic law when it is done in the usual manner without any change. And since by Torah law these activities are permitted, in Surya they may be done on Shemittah without any change at all: threshing, winnowing, treading and gathering into sheaves.
What case is being discussed?
Most commentators understand that the mishnah is dealing with guarded produce, that is, produce that was kept for oneself, where a person did not properly declare his fruits ownerless and did not allow anyone to come and take a share of his produce during Shemittah. Since he guarded it, these restrictions were stated regarding what he is permitted to do and what he is forbidden to do. But if he did declare his fruits ownerless, he would have been permitted even to harvest grain and to pick grapes in the fully normal manner, according to most commentators.
In summary: In this mishnah we learned that Surya, which was conquered by King David before the conquest of all of Eretz Yisrael, did not receive the full sanctity of the Land. Therefore during Shemittah it is permitted there to work with produce detached from the ground - threshing, winnowing, treading and gathering into sheaves - and it is forbidden to work with produce attached to the ground: harvesting grain, picking grapes and picking olives. Rabbi Akiva's rule: whatever is permitted in Eretz Yisrael by Torah law and forbidden there only by rabbinic law may be done in Surya with no change whatsoever. All of this applies to guarded produce that was not properly declared ownerless, but with fruits that were declared ownerless, even harvesting grain and picking grapes are permitted.