Imprisonment by authorities other than a rabbinical court
Rav Nachman designed an entranceway [Tzurat haPetach] permitting transport in an alley on Shabbat on behalf of the Exilarch [Reish Galuta]. Rav Sheshet had a different opinion regarding its validity, and he told his assistant, Rav Gada, to remove it. The Exilarch's servants found Rav Gada and imprisoned him. Rav Sheshet stood by the prison gate and said, "Gada, Emerge!" Rav Gada emerged. Rav Sheshet later encountered Rabbah bar Shemuel and asked him whether he had anything to teach regarding entranceways, and Rabbah bar Shemuel taught that such an entrance would be valid. Rav Sheshet responded, "Don't teach that to the Exilarch's household! [I will recant on my own - Rabbeinu Chananel]": Eruvin 11b
