Our Gemara relates that Rabban Gamliel accidentally injured his non-Jewish slave, Tavi, blinding him, and that Rabban Gamliel rejoiced – because finally Tavi would be set free – based on the passage in Sefer Shemot 21:26, which establishes that slaves go free if their master injures them by blinding them or knocking out a tooth. Upon sharing the happy news with Rabbi Yehoshua and explaining the circumstances leading to Tavi’s freedom, Rabbi Yehoshua informed him that Tavi would not go free. Since there were no witnesses to the event, and the slave’s freedom was based on Rabban Gamliel’s own admission, the penalty assessed on the master would not take effect, since modeh be-kenas patur – someone who admits his guilt is not assessed penalties – as we learned previously on daf 64.
Tavi is a character who appears throughout the Gemara, identified as the slave belonging to Rabban Gamliel of Yavne. In all of these stories he is presented as someone who was well-known for his personal piety and learning. Not only Rabban Gamliel, but other sages sang his praises. Rabbi Elazar ben Azarya, for example, was known to say that based on Tavi’s Torah knowledge it would have been appropriate for Tavi to be reclining and for Rabbi Elazar to be serving him. Rabban Gamliel tried on several occasions to find a way to set him free, but was stymied in his efforts because of the prohibition to set Canaanite slaves free. Nevertheless, when Tavi passed away, Rabban Gamliel accepted consolation as if he was a family member, explaining that Tavi was different than other slaves ? he was a good and honest man.
The Mishna in Massekhet Sukka (20a) closes with Rabbi Shimon’s testimony about Rabban Gamliel’s slave, Tavi, who would sleep under the bed in the sukka. According to Rabban Gamliel he did so specifically because he knew that non-Jewish slaves were not commanded in the mitzva of sukka, from which we can derive that someone obligated in the mitzvahwould not be permitted to do so.