http://www.ou.org/shabbat_shalom/article/masechet_ketubot_111112/Ketubot 111a-bBased on passages in Shir ha-Shirim (2:7, 3:5, 8:4), Rabbi Yossi ben Rabbi Hanina understands that there are three oaths that bind the Jewish people in their relationship with the non-Jewish world:
1. That the Jews should not return to the Land of Israel be-homah – "like a wall"
2. That the Jews should not rebel against the nations of the world
3. That the nations of the world should not oppress the Jewish people overmuch.
Rashi interprets the first oath to mean that the Jewish people should not return to Israel by force, all together (in fact, some manuscripts have ka-homah, which would indicate "all together"). The Maharsha argues that it refers to the actual building of a wall – which would indicate a rebellion against the ruling nation. Such building could not be done without the permission of the nations that ruled over the land, as took place with the return of Ezra and Nehemia at the beginning of the Second Temple era.
Based on his reading of the pesukim (=verses) in Shir ha-Shirim, Rabbi Levi believed that each passage implied a double oath. Aside from the three mentioned above, he adds three more:
4. That the end (ketz) should not be revealed
5. That the end should not be pushed off
6. That the secret should not be shared with the non-Jews.
Rashi understands that the fifth oath is a warning that sins and transgressions will delay the Messianic end of days, while the Maharsha suggests that it means that the people should not push off the ends of days in their hearts, but that they should believe that the Messiah will come swiftly.
There are also a wide variety of opinions regarding the secret that cannot be shared with non-Jews. While Rabbenu Tam believes that it is the secret of the Jewish calendar and Rabbi Avraham Ya'akov Neimark in his Eshel Avraham suggests that it refers to the oaths that are under discussion, it may not be connected with a religious issue at all. In a mosaic floor that was found in Ein Gedi, a curse is placed on the person who reveals the secret of the city to non-Jews. It is an apparent reference to a security secret; a way to enter the city.
http://www.dafyomi.co.il/kesuvos/halachah/ks-hl-111.htm