Gemara

(R. Yochanan): R. Akiva says that Zerikah is effective for Yotzei only if some (of the meat or Eimurim) remained inside, but not if all left.

Rav Asi: My colleagues in Bavli taught me that intent (for Pigul) takes effect on what was lost or burned.

i. Even though they are not present, intent takes effect on them.

Berachos 27b (Beraisa - R. Eliezer): The following cause the Shechinah to depart from Yisrael: ... one who argues with his Rebbi's teaching, or says something that he did not hear from his Rebbi.

Yevamos 96b: R. Elazar said a teaching, but did not attribute it to R. Yochanan. R. Yochanan was upset when he heard about this.

R. Yakov bar Idi: "As Hash-m commanded Moshe His servant, so Moshe commanded Yehoshua..."

Did Yehoshua say about everything 'Moshe told me so'?! Rather, he expounded, and everyone knew that he learned his Torah from Moshe;

Also R. Elazar your Talmid expounds, and everyone knows that it is your teachings!

Kesuvos 25b: A man (to Reish Lakish): I know that Reuven is a Kohen, because he read first in the Torah.

Reish Lakish: Did you see him receive Terumah at the granaries?

R. Elazar: Do you hold that if there are no granaries, we cannot establish anyone to be a Kohen?!

Later, Reish Lakish realized that R. Elazar heard this from R. Yochanan. He angrily rebuked him for not saying it in the name of R. Yochanan.

Sanhedrin 99b: An Apikorus is a Talmid who cites a teaching saying 'we said such and such there', and does not attribute the teaching to the Rebbi.

101a - R. Eliezer: Is there any Mitzvah that I did not fulfill (that you consider me worthy of suffering)?

R. Akiva: You taught us "Adam Ein Tzadik ba'Aretz... v'Lo Yecheta."

Chagigah 14b: R. Elazar ben Arach asked R. Yochanan ben Zakai to teach to him Ma'ase Merkavah.

i. R. Yochanan: One may teach it only to one who understands by himself.

i. R. Elazar: Allow me to say one thing that you taught to me!

i. R. Yochanan descended from his donkey. He explained 'if you will expound Ma'ase Merkavah, the Shechinah and angels will be here.'

Mo'ed Katan 9a: R. Yonason ben Amsai and R. Yehudah ben Gerim were learning from R. Shimon. They took leave of him at night. The next morning, they came to take leave of him.

R. Shimon. You already took leave of me last night!

R. Yonason and R. Yehudah: Rabbeinu, you taught to us that if a Talmid takes leave of his Rebbi and lodges in the city, he must take leave of him again in the morning!

Contradiction: It says "ba'Yom ha'Shmini (on the eighth day of Sukos) Shalach Es ha'Am va'Yvarchu Es ha'Melech", and it says "ba'Yom Esrim u'Sheloshah la'Chodesh ha'Shevi'i Shalach Es ha'Am"!

Answer: This teaches that if a Talmid takes leave of his Rebbi and lodges in the city, he must take leave of him again.

Nazir 56b (Mishnah - R. Elazar, citing R. Yehoshua): One is liable for entering the Mikdash b'Tum'ah only if his Tum'ah nullifies Nezirus.

Question: A Beraisa teaches that R. Elazar did not learn this from R. Yehoshua, rather from R. Yehoshua bar Mamal!

Answer: This teaches that when a teaching was transmitted through three (or more) Chachamim, it suffices to mention the first and last.

Support (Rav Nachman bar Yitzchak - Mishnah - Nachum ha'Lavlar): If one plants dill and mustard in two or three places, he must leave Pe'ah from each. I received this law from R. Miyosha, and he from my father, and he from the pairs (the Nasi and Av Beis Din), and they from the Nevi'im, and they from Moshe, who received this on Sinai.

He did not mention Yehoshua and Kalev. This shows that one may omit intermediate steps in the chain.

Chulin 30b: An ox was slaughtered in two or three places. R. Yitzchak bar Shmuel took from the choice parts to eat.

R. Zeira (to Rav Yitzchak): Rebbi, didn't you teach to us that the Mishnah permits Shechitah done by two people (only) when they hold one knife?!

Megilah 15a (R. Elazar): Whoever repeats something in the name of the one who said it brings redemption to the world - "Esther told the king in the name of Mordechai."

Rishonim

Rambam (Hilchos Talmud Torah 5:9): If one sees his Rebbi transgress Divrei Torah, he says 'Rabbeinu, you taught to us such and such.' Whenever one says a teaching in front of his Rebbi, he says 'so you taught to us.' He may not say something he did not hear from his Rebbi until he says the one who said it. This refers to Rabo Muvhak, who taught to him most of his Chachmah. If he did not learn from him most of his Chachmah, he is a Talmid Chaver, and he need not do so.

Kesef Mishneh: The Gemara says regarding a parent that he does not say 'you transgressed.' The Rambam learns that all the more so, this applies to Rabo Muvhak. Berachos 27b connotes that one may say Stam something that he heard from his Rebbi, without mentioning his Rebbi. This is because presumably, whatever he says he heard from his Rebbi, like it says (in Yevamos).

Maharatz Chayos (30b DH Tosfos): Our Gemara is a proof for the Rambam, that also when correcting one's Rebbi one must say 'you taught to us.'

Rosh and R. Yonah (Berachos 4:5 and Berachos 18b): One who says in the name of his Rebbi something that he did not hear from his Rebbi causes the Shechinah to depart from Yisrael.

Poskim

Shulchan Aruch (YD 242:22): If one sees his Rebbi transgress Divrei Torah, he says 'Rabbeinu, you taught to us such and such.'

Erech Lechem: One may say incredulously in front of his Rebbi 'is this the Halachah'?!

Shulchan Aruch (23): Whenever one says a teaching in front of his Rebbi, he says 'so Rabbeinu taught to us.'

Gra (59): We learn from Sanhedrin 99b. This is even if he did not learn this from his Rebbi, like we find in Mo'ed Katan, Chagigah and Sanhedrin 101a.

Erech Lechem: Sanhedrin 101a connotes that one must say one must say 'Rabbeinu, you taught to us' even regarding a verse.

Maharsha (Chagigah 14B DH v'Lo): If R. Yochanan ben Zakai thought that R. Elazar ben Arach is not worthy to learn Ma'ase Merkavah, why did he initially teach to him? He taught to him before R. Elazar forgot his learning. Alternatively, he had not taught to him. R. Elazar said 'you taught to us' due to humility.

Iyun Yakov (DH Tarsheni): R. Yochanan had taught to him the chapter headings, and R. Elazar (the entire matter) by himself. (This is the only way to learn Ma'ase Merkavah.)

Shulchan Aruch (24): He may not say something he did not hear from his Rebbi until he says who said it.

Bach (7): The Gemara forbids saying something that he did not hear from his Rebbi. The Rosh and R. Yonah explain that he heard it from someone else, and says it in the name of his Rebbi. This connotes that he may say it Stam. This is difficult, for Chachamim exhorted to say something in the name of the author! If he did not hear this from anyone, just he thought of it himself, what is wrong if he says it Stam? The Rambam's Perush is correct. He heard it from someone else, and says it Stam. Chachamim warned against this; it causes the Shechinah to depart. This implies that one may say Stam a teaching that he heard from his Rebbi, like the conclusion in Yevamos. This is only if it is known that the Talmid did not learn from another Rebbi, like Yehoshua and R. Elazar, who learned only from Moshe and R. Yochanan, respectively. If he learned from two Rebbeyim, one must say which taught the teaching.

Gra (60): The Yerushalmi says that R. Meir said a teaching in the name of R. Yishmael, but he did not say (teachings) in the name of R. Akiva, for all know that he is R. Akiva's Talmid (so what he says Stam is from R. Akiva. However, the Bavli (Eruvin 13a) says that he learned from both of them! - PF)

Divrei Chamudos (Berachos 4:24): If one will say Stam something he did not hear from his Rebbi, perhaps it is wrong, this disgraces the Rebbi.

Shach (43): Nowadays, when someone says a teaching, people assume that he taught it himself. Therefore, the law changed. If one heard something from others, surely, he may not say Stam, and all the more so in his own name. This is adorning himself with another's cloak!

Birkei Yosef (28): When a teaching was transmitted through three (or more) Chachamim, it suffices to mention the first and last (Nazir 56b). It is praiseworthy to mention those in the middle. Sometimes the Gemara brings a teaching in the name of four or five Chachamim. The Yerushalmi says that if one can trace the teaching back to Moshe, he should. If not, not he mentions the first and last.

Shem ha'Gedolim (Sefarim, 7:26 DH v'Hinei): When people say a Chacham's teachings, his lips move in the grave whether or not they said it in his name. R. Yochanan was particular that his teachings be said in his name, for then people will accept them and repeat them. Reish Lakish would have accepted R. Elazar's words if he knew that R. Yochanan said it, therefore he was angry. He held that R. Elazar considered himself to be a Talmid Chaver, who may say his own teachings. We attribute teachings of a total Talmid to his Rebbi.

Rashash (Chulin 30b DH Limadtani): Tosfos explains that Rav Yitzchak retracted, because R. Zeira said 'you taught me...' Also Rashi (42b DH Amrei) says that Amora'im argue about Rav's opinion because Rav Kahana and Rav Asi said 'you taught to us'. However, the Rambam and Shulchan Aruch say that one must say to his Rebbi 'you taught to me' even if he did not learn it from him. The Gra brought proofs for this. I add a proof from Rosh Hashanah 25a. In a Beraisa, R. Akiva asked R. Yehoshua 'may I say something that you taught to me?' In the Mishnah, he said the same Drashah 'I can learn', which shows that he did not hear it from R. Yehoshua!

Note: It is clear that the Mishnah discusses the same episode. It seems to argue about the words R. Akiva said. If so, we should rule like the Mishnah, that it is not a Chiyuv to say so! However, Rebbi made the Mishnayos brief, so perhaps it teaches concisely that R. Akiva himself expounded this, and the Beraisa elaborates to give his exact words.

Rashash (ibid.): However, in Me'ilah, Rav Asi said to R. Yochanan 'my colleagues taught to me...', and it seems that Rav Asi was R. Yochanan's Talmid! This is somewhat difficult.

Note: Surely one does not say 'you taught to me' when challenging his Rebbi, unless it is from a source that his Rebbi cannot argue with, e.g. a verse or Beraisa! However, Tosfos (6b DH Amar) says that Rav Asi merely taught this. He did not challenge R. Yochanan. Presumably, the Rashash says that this is only somewhat difficult because the Rambam and Shulchan Aruch discuss only Chidushim of the Talmid himself, but when he cites others, he must say it in their name!