Reference for Sheviit 6:5

אֵין מוֹצִיאִין שֶׁמֶן שְׂרֵפָה וּפֵרוֹת שְׁבִיעִית מֵהָאָרֶץ לְחוּץ לָאָרֶץ. אָמַר רַבִּי שִׁמְעוֹן, שָׁמַעְתִּי בְפֵרוּשׁ, שֶׁמּוֹצִיאִין לְסוּרְיָא וְאֵין מוֹצִיאִין לְחוּץ לָאָרֶץ:

It is not permitted to export oil that must be burnt [because it is <i>Terumah</i>, produce consecrated for priestly consumption, that has been made impure] and the fruits of the Sabbatical year from the Land [of Israel] to other lands. Rabbi Shimon said, I explicitly heard that it is permissible to export to Syria, but it is not permissible to export to other lands.

Jastrow