GEMARA

20b (Mishnah): If Reuven said 'I am a Nazir'; another (heard him and) said 'and I'; (and another said) 'and I', they are all Nezirim.

(Gemara - Reish Lakish): This is when each said 'and I' Toch Kedei Dibur;

This is the time needed to greet someone with Shalom, i.e. the time needed for a Talmid to greet his Rebbi (Shalom Alecha Rebbi).

Objection (R. Yehudah Nesi'ah): If a Talmid wanted to accept Nezirus like Reuven, and his Rebbi came, he will not have time. He must greet his Rebbi, and then it is too late to say 'and I'!

Support (for Reish Lakish - Beraisa): If Reuven said 'I am a Nazir', Shimon paused Kedei Dibur, and said 'and I', Reuven is a Nazir, but Shimon is not. Kedei Dibur is the time for a Talmid to greet his Rebbi.

Bava Kama 73a (Beraisa): If witnesses testified that Levi stole and slaughtered, and they were Huzmu about (others testified that they were not there to witnesses) the slaughter, Levi pays double, and the witnesses pay triple;

R. Yosi says, this applies to two testimonies. Regarding one testimony, partially nullified testimony is totally nullified (Levi is exempt).

'Two testimonies' means like two testimonies, one after the other. One testimony is when they testified about the theft and slaughter together.

Assumption: Both Tana'im hold that anything done Toch Kedei Dibur is k'Dibur (a continuation of the previous matter). They argue about whether or not Zomemim witnesses are disqualified retroactively from when they testified falsely.

Rejection: No, they argue about whether or not Toch Kedei Dibur is k'Dibur. Chachamim say that it is not k'Dibur. R. Yosi says that it is.

Question (Mishnah - R. Yosi): If one said 'this is Temuras Olah', then reconsidered and said 'Temuras Shelamim', it Temuras Olah.

Question: This is obvious!

Answer (Rav Papa): He reconsidered Toch Kedei Dibur. (This shows that R. Yosi holds that Toch Kedei Dibur is not k'Dibur!)

Answer: There are two measures of Toch Kedei Dibur: a Talmid greeting his Rebbi (Shalom Alecha Rebbi u'Mori, four words), and a Rebbi greeting his Talmid ('Shalom Alecha, two words). R. Yosi holds that within the shorter time is k'Dibur, but (after this and) within the longer time is not k'Dibur.

Temurah 25b (Mishnah - R. Yosi): If he said 'it is a Shelamim', then reconsidered...

Objection: Obviously, one may not retract his Hekdesh at any future time!

Answer (Rav Papa): The case is, he retracted Toch Kedei Dibur. One might have thought that Toch Kedei Dibur is k'Dibur. The Mishnah teaches that this is not so.

Nedarim 87a: The Halachah is, one may retract or correct anything within Toch Kedei Dibur, with four exceptions: blasphemy, idolatry, Kidushin, and divorce.

Shevuos 32a (Mishnah): If both witnesses simultaneously denied knowing...

Question: It is impossible that two events (their denials) occur simultaneously!

Answer #1 (Rav Chisda): The Mishnah is R. Yosi ha'Galili, who says that it is possible for that two events to occur simultaneously.

Answer #2 (R. Yochanan): The Mishnah can even be Chachamim; the case is, they denied within Toch Kedei Dibur of each other; it is as if they denied at once.

Anything said Toch Kedei Dibur is k'Dibur.

(Rav Acha mi'Difti): Toch Kedei Dibur is the time needed to greet one's Rebbi.

Zevachim 30b: R. Meir holds that if one said 'Temuras Olah Temuras Shelamim', he tried to retract (but he cannot). Had he wanted both to take effect, he would have said 'Temuras Olah v'Shelamim.'

RISHONIM

Question (Tosfos Bava Kama 73b DH Ki): Why does Rav Acha mi'Difti allow the time for a Talmid to greet his Rebbi? Only R. Yosi holds that that Toch Kedei Dibur is k'Dibur, and he allows only the time for a Rebbi to greet his Talmid!

Answer (Tosfos): Rav Acha mi'Difti holds like the Beraisa in Nazir, which says that Toch Kedei Dibur is k'Dibur. The Gemara in Nedarim rules like it. This is the time for a Talmid to greet his Rebbi, like Rav Acha and Reish Lakish.

Question (Mishneh l'Melech, Hilchos Ma'aseh ha'Korbanos 15:1): What is Tosfos' answer? How do we learn the Shi'ur from Nazir and Nedarim?

Answer (Ketzos ha'Choshen 255:2): The Beraisa in Nazir explicitly says that the Shi'ur is for a Talmid to greet his Rebbi.

Rambam (Hilchos Ma'aseh ha'Korbanos 15:1): If one decided in his heart and said 'this (pregnant) animal is a Shelamim', and retracted and said 'and its fetus is an Olah', even if he retracted Toch Kedei Dibur, the fetus is a Shelamim. One cannot retract Hekdesh, even Toch Kedei Dibur.

Kesef Mishneh: Rav Papa says so in Temurah 25b.

Question: Nedarim 87a did not list Hekdesh among the four exceptions!

Answer #1 (Radvaz): We do not learn from a general rule, even when it lists the exceptions (Eruvin 27a). One cannot retract because Amirah l'Gavoha (saying 'this is Hekdesh') is like Mesirah (giving over) to a person. Chachamim did not make Toch Kedei Dibur like Dibur for the four exceptions because they are stringent (Ran). Also Hekdesh and Temurah are stringent!

Ketzos ha'Choshen (255:2): One can retract Toch Kedei Dibur from Mesirah to a person, because it depends on Amirah. Amirah l'Gavoha works by itself. This does not apply to Hekdesh Aniyim, so Toch Kedei Dibur helps for it.

Answer #2 (Radvaz): The Gemara in Nedarim does not discuss Hekdesh. It is not clear what is the source for this.

Answer #3 (Ri Korkus): Some texts in Nedarim (e.g. of Tosfos Menachos 81b DH Todah) list Hekdesh among the exceptions.

Question (against all three answers - Shach CM 255:5): In Bava Kama, the Gemara asked from Hekdesh to other matters, and distinguished between Shi'urim of Toch Kedei Dibur. It did not say that Hekdesh is an exception!

Answer (Mishneh l'Melech): The Rambam rejected the Gemara in Nedarim due to Tosfos' question. He concluded that the Gemara in Bava Kama is like the opinion that Kedei Dibur is to greet one's Talmid. This resolves the contradiction in R. Yosi. The opinion that allows Kedei Dibur to greet one's Rebbi must say that Toch Kedei Dibur does not help for Hekdesh, to resolve R. Yosi. Zevachim 30 proves that even R. Meir agrees that one cannot retract from Hekdesh (even Toch Kedei Dibur). In Temurah, we answered that the Chidush of the Mishnah is that we do not say that (he did not retract, rather,) he was thinking about the Hekdesh. It should have said that the Chidush is that even though everywhere else Toch Kedei Dibur is k'Dibur, here it is not!

Perush ha'Mishnayos (Temurah 5:3): Toch Kedei Dibur is k'Dibur, except for one who is Makdish or makes Temurah, blasphemy, idolatry, Kidushin, and divorce.

POSKIM

Shulchan Aruch (CM 255:3): If one was Makdish all his property, he is not believed to say 'I owed Ploni' or 'this Keli is Ploni's.'

SMA (14): Ir Shushan says that he cannot retract even Toch Kedei Dibur. This is wrong. This is not one of the four exceptions.

Ketzos ha'Choshen (2): Retraction Toch Kedei Dibur makes the original Dibur like a mistake, so it does not help for Temurah, in which mistaken Hekdesh is Hekdesh (Nazir 31a). We find that R. Yosi equates Hekdesh and Temurah regarding retraction. This is a stringency of Hekdesh.