The Mishnah in Maseches Eduyos teaches: Who did they excommunicate? Elazar ben Chanoch, who belittled the concept of only a person's hands being impure. (Note: This understanding is taken from Rav Chaim Kanievski's explanation). This shows that one who doubts even a Rabbinic decree must be excommunicated.

The Mishnah in Maseches Eduyos teaches: Akavya claimed that Shemayah and Avtalyon gave fake Sotah water to drink to a freed slave woman who was a convert. (Some explain that he spoke disparagingly about their ruling to give her to drink, saying that they did so because they were also converts). The Chachamim excommunicated him and he died in this state. The Beis Din stoned his casket, thereby teaching that whoever dies in a state of excommunication has his casket stoned. This case teaches us that one who speaks derogatorily about a Sage, even after his death, must be excommunicated.

In the days of R. Zeirah they would excommunicate a person and then immediately release him.

R. Ila to Rabbanan: How can you immediately release him (if the minimum period for excommunication is 30 days)?

R. Yosa: The Chachamim therefore retracted and ruled that they release and accept him immediately as soon as he repents.

When they excommunicate a Rav, his student must act as if excommunicated. But if they excommunicate a student, his Rav does not need to act as if excommunicated.

When they excommunicate the head of the Beis Din, a Sage must act as if excommunicated. But if they excommunicate a Sage, the head of the Beis Din does not need to act as if excommunicated.

When they excommunicate the Nasi, all must act as if excommunicated.

Question: We have discussed a Chacham, but what if a Chaver (a person trusted about tithing and maintaining Taharah) was excommunicated?

Answer: A slavewoman of Bar Peteh once passed by a synagogue. She saw a teacher excessively hitting a child and she excommunicated him. He came before R. Acha and R. Acha told him that he must be concerned for her excommunication. This shows that one who acts in an improper way must be excommunicated.

R Shimon ben Lakish was once guarding figs in Barbaris. Thieves came and stole them from him at night. Eventually, R"SBL realized who were the thieves and he declared that they should be excommunicated.

They responded by excommunicating R"SBL.

R"SBL was concerned and he said, "They owe me money but do they deserve excommunication?" He thought that perhaps he deserved excommunication since he unlawfully excommunicated them. He chased them and begged them to release his excommunication.

They replied: You release our excommunication and we will release yours.

This shows that one who excommunicates someone who does not deserve it, and that person in turn excommunicates him back, it is valid.

Question: Who could release such an excommunication if those who made it cannot be found? (If R"SBL did not find the thieves, who could have released him?)

Answer: Did we not learn in a Beraisa that if one of those who excommunicated died, we cannot release the excommunication; and R. Yehoshua ben Levi explained that this is true only when there is no Nasi, but if there is, the Nasi can release it!

Question (R. Yaakov bar Acha quoting R. Ba bar Mamal): There was once an excommunicated person and one of those that excommunicated him died and the Chachamim did not release him! Did R. Yehoshua B"L not say that this applies when there is no Nasi there, but if there is a Nasi, he can release the person?

Answer: We can say that R. Ba's case is that the reason that the Nasi did not release him is because he did not repent for his sin. It is only because the one who excommunicated died, but if he would be alive, he could release him even if the person did not repent.

R. Yaakov bar Abayei quoting Rav Sheshes: They agreed in Usha that one may not excommunicate an elder.

This follows the statement of R. Shmuel quoting R. Abahu - If an elder acted in a way that made him worthy of excommunication, we do not remove him from his position; rather, we tell him, as the Pasuk states (Melachim 2, 14, 10), "Make yourself heavy (like someone who is feeling unwell and his head is heavy) and sit at home".

R. Yaakov bar Abayei quoting R. Acha: An elder who unintentionally forgot his Torah knowledge is treated with the holiness of the Holy Ark.

R. Acha/ R. Tanchum/ R. Chiya quoting R. Yochanan: If an elder excommunicated himself, even if done for a valid reason, it is not a valid excommunication.

In the days of R. Yirmiyah, a trouble befell the people of Tiveria (and they needed a large sum of money to appease the enemies).

They sent a message to R. Yaakov bei R. Bun, asking him to donate a silver candelabra to the collection.

He sent a message back - "[R.] Yirmiyah has still not repented from his evil (that he wishes to levy payments on the Torah Sages)". R. Yirmiyah wished to excommunicate R. Yaakov B"RB. R Chiya ben R. Yitzchak of Atushiya was sitting there.

Question (R. Chiya to R. Yirmiyah): I heard that one may only excommunicate an elder if he behaved like Yeravam ben Nevat and his followers?

R. Yirmiyah responded: When they excommunicated Akavia (see above 16-1) (b)), had he behaved like Yeravam ben Nevat?

The Mishnah had taught: One whose vow was permitted by a Chacham.

What is the case? If he asked before the festival, he may not take a haircut. If he did not ask before the festival, he also may not take a haircut! Rather, he asked before the festival and the Chacham did not find a way to permit it until the festival...

It is like the case of R. Shimon ben Rebbi - they did not find a way to permit his vow until one of the elders of the Galil came.

Some say that the elder from the Galil was R. Shimon ben Elazar. Several times, R Shimon B"E took R. Shimon B"R from here to there discussing the matter with him, attempting to find a reason to permit the vow. R"SBR began to delouse his garments, because of the hot sun.

They said to R"SBR - if you would have known that this elder would take you from place to place in order to find a reason to permit your vow, would you have made the vow? R"SBR said - no. As a result of this answer, the elder permitted his vow.

They asked the elder - what is the source for this?

He replied - I was R. Meir's servant when he fled for the second time (and I saw him permit a vow in this way).

Some say that the staff of R. Meir was in his hand and it taught him understanding (i.e. he became wiser during the time he served R. Meir).