We just learned from "u'Banim AL Avosam" that an uncle is disqualifies from testifying on his nephew and vice-versa. We know that brothers are disqualified too - because the relationship between uncle and nephew stems from the fact that they are the offspring of two brothers (who are therefore disqualified through a 'Kal va'Chomer').

We learn from the fact that the Torah writes "Banim" in the plural that - cousins are disqualified too.

Rami bar Chama initially learns from a Beraisa - which requires both witnesses to become Zom'min, for the Din of Zom'min to take effect, that two relatives cannot testify for a stranger ...

... because if they could, then each witness would become a Zomem through the testimony of a relative.

The Mishnah in Bava Basra 'Sheloshah Achin ve'Echad Mitztaref imahen ... ' concludes - 'Harei Eilu Sheloshah Iduyos, ve'Hein Eidus Achas le'Hazamah'.

From there, Rava refutes Rami bar Chama's source - because by the same token, each of the witnesses there would become an Eid Zomem through his brother's testimony (which ought therefore to be discounted).

According to Rava therefore, it is not the co-witnesses' testimony that makes them Zom'min - but the witnesses who are Mazim them.

And Rava learns Rami bar Chama's Din from the Lashon "u'Vanim" (when it could have written "u'Vein al Avos" or "ve'heim al Avos"), teaching us that brothers cannot testify for strangers.

From the second ...

... "Banim" ("u'Vanim Lo Yumsu al Avosam") via 'Im Eino Inyan', we learn that - the relatives of one's mother have the same Din as those of one's father.

... "Yumsu" (when it could have written "u'Vanim al Avosam"), we learn that - just as one cannot testify against one's relatives, so can one not testify on their behalf either.

And from the Pasuk "Mishpat Echad Yih'yeh lachem" we learn that - relatives are even disqualified from testifying in Diynei Mamonos, as well as Diynei Nefashos.

When we say that our Mishnah ...

... disqualifies 'SHeini be'Rishon and SHeini be'SHeini', we are referring to - 'Achi Aviv' and 'B'no', respectively.

... does not disqualify 'Shelishi be'Rishon', we mean that - the Tana does not disqualify a person's son from testifying on his father's brother.

Rav disqualifies a person, as well as his son or his son-in-law, from testifying on 'Achi Aba, hu u'Beno ve'Chasno ... and his father's brother from testifying for him, his son or his son-in-law.

To reconcile Rav with our Mishnah, we reinterpret 'Achi Aviv Hu u'Beno ve'Chasno' to mean that - neither he, nor his son nor his son's son-in-law (a Shelishi be'Rishon) may testify on his father's brother.

And the reason that the Tana presented the case of Chasan B'no (rather than that of Ben B'no) is - to teach us that a husband has the same status as his wife.

When Rebbi Chiya says that our Mishnah lists eight Avos which are twenty-four, he means that - although the Tana lists only eight relations that are disqualified from testifying, seeing as this incorporates each one's son and son-in-law, there are really twenty-four.

This disproves Rav's earlier statement equating 'Chasno' with 'Chasan B'no' - because Rebbi Chiya ought then to have referred to eight Avos which are thirty-two (incorporating himself, his son, his son-in-law and his son's son-in-law).

Even though 'Chasno' does not in fact, mean Chasan B'no, Rav nevertheless refers to him as such - because whoever is not a blood-relative, descends one rung in the ladder.

We might then have queried the Mishnah's ruling which forbids one's son-in-law to testify for his own father's brother in that - based on this theory, this would be a case of Revi'i be'Rishon (which nobody would ever dream of disqualifying).

We finally disprove Rav completely from the Mishnah's ruling forbidding one's father's brother's son-in-law from testifying on his behalf - because again, based on the current theory, this would be a case of Shelishi be'SHeini, whose testimony Rav himself validates.

So we finally establish Rav like Rebbi Elazar, who says in a Beraisa - 'ke'Shem she'Achi Aba Lo Ya'id li, Hu, u'Beno ve'Chasno, Kach ben Achi Aba Lo Ya'id li, Hu, u'Beno ve'Chasno' (although he is only a Shelishi be'SHeini).

Rav extrapolates from there that - a Shelishi be'Rishon is certainly forbidden (and with that he agrees).

Rav derives this from the extra 'Vav' in the word "u'Vanim" (in the Pasuk "Lo Yumsu Avos al Banim u'Vanim") - disqualifying a man from testifying, not only on behalf of his father's brother, but also on behalf of his grandfather's brother (a Shelishi be'Rishon).

Rebbi Elazar extends the D'rashah of Rav - by Darshening "al Banim" to mean that the P'sul of the fathers extends to the children (thereby disqualifying even a Shelishi be'SHeini).

We rule like Rav, but not like Rebbi Elazar.

Rav Nachman rules that the brother of a person's mother-in-law, the latter's son and his sister's son - may not testify on his behalf.

And we prove it from our Mishnah - which disqualifies the testimony of 'Ba'al Achoso, Ba'al Achos Aviv u'Ba'al Achos Imo, Hein u'Veneihen ve'Chasneihen' (which are synonymous with the three above cases).

've'Tana Tuna' means - 'and the Tana (in our Mishnah) learns like that'.

When they asked Rav whether a person may testify on behalf of his stepson's wife, whose Nechsei Milug are being disputed - he was coming to sell Gevilin (parchment for Sifrei-Torah).

They did not ask him the same She'eilah about the wives of other relatives - because, seeing as their sons are forbidden to testify on his behalf, and the sons inherit their mothers, it is obvious that he would not be able to testify on her behalf.

In Sura they replied 'Ba'al ke'Ishto', in Pumbedisa' - Ishah ke'Ba'alah, which is effectively the same thing (either way, disqualifying a man from giving testimony on behalf of his stepson's wife).

Rav Huna Amar Rav learns from the Pasuk "Ervas Achi Avicha Lo Segaleh, el Ishto Lo Sikrav, Dodascha hi" - the principle 'Ishah ke'Ba'alah'.

We learned in our Mishnah 'u'Ba'al Imo Hu u'Beno ... ', which Rebbi Yirmiyah explains to mean - Achi ha'Ach (the son of his step-father from another wife [so as not to be synonymous with 'Achiv']), who is Pasul because he is his half-brother's half-brother.

Rav Chisda disagreed with this ruling. According to him, the Kashya that we just asked remains. In his opinion - the Tana presents the case twice, once by a paternal brother and once by a maternal brother.

Rav Chisda - permits the father of a Chasan and the father of the Kalah to testify on each other's behalf, since they are no closer than the lid of a barrel that is placed on the barrel, but not cemented to it.

Rabah bar bar Chanah permits a man to testify in a case involving his betrothed wife. Ravina qualifies this ruling - by restricting it to extracting the Nechsei Milug from her with his testimony, but not of establishing them in her possession (since he then stands to gain and is obviously prejudiced).

Ravina probably learns this from a statement of Rav Chiya bar Ami in the name of Ula - that the laws of Onein (the prohibition of eating Kodshim), burial, and inheritance do not come into effect by an Arusah (because they are basically still considered strangers).

He does however, allow her to claim her Kesubah should her Chasan die - in the event that he wrote her one.

We reject the proof from there however on the grounds that - whereas there, the criterion is whether the woman is considered 'She'eiro' (his real wife) or not (and an Arusah is not), the criterion with regard to testifying is whether he stands to gain or not.

One Beraisa states 'Chorgo Levado. Rebbi Yossi Omer Giso'. Bearing in mind that it is Rebbi Yehudah who argues with Rebbi Yossi, another Beraisa says - 'Giso Levado. Rebbi Yehudah Omer Chorgo Levado'.

Rebbi Yossi cannot possibly permit the son of Giyso to testify - because it is synonymous with 'Ba'al Achos Imo'.

He nevertheless says 'Giso Levado' - because ben Giso is not disqualified, and the ramifications of this statement are that Chasan Giso is permitted to testify.

Rebbi Yossi cannot be referring to the son of Giso but from a different wife (to solve the above problem), because a. all the 'Beneihem' mentioned by the Tana'im refer to the son from the same wife, and b. - since it would imply that the Tana Kama disqualifies even such a son, how could Rav Chisda then validate the testimony of Achi ha'Ach, which is closer than ben Achos Ishto.

Both Tana'im cannot be saying that neither the son nor the son-in-law may testify on behalf of either Chorgo or Giso (in which case, each one will be making a different statement, even though they both agree ['Mar Amar Chada, u'Mar Amar Chada, e'Lo Peligi']) - because then the author of our Mishnah 'Giso, Hu u'Beno ve'Chasno' will be neither Rebbi Yehudah nor Rebbi Yossi.

And the Tana Kama of the first Beraisa cannot hold 'Chorgo Levado', Aval Giso, Hu u'Veno ve'Chasno, and Rebbi Yossi, the reverse - because then Rebbi Chiya's Beraisa (that we quoted earlier) 'Shemoneh Avos she'Hein Esrim ve'Arba'ah', will hold like neither Tana, according to both of whom there are nine Avos, and not eight.

Both the Mishnah and the Beraisa will be served, if we explain the Beraisa 'Chorgo Levado, Aval Giyso, Hu, u'Veno ve'Chasno. Rebbi Yossi Omer Giso Levado, ve'Kol she'Kein Chorgo' (and that is how we will the second Beraisa, too) - because then our Mishnah will go like Rebbi Yehudah, and the Beraisa, like Rebbi Yossi.

Rav Yehudah Amar Shmuel rules - like Rebbi Yossi.

Rav Yosef wanted to validate a Sh'tar Matanah on which two brothers-in-law had signed - because he thought that Rav Yehudah Amar Rav's previous ruling was referring to Rebbi Yossi in our Mishnah, who validates Giso (since he confines the prohibition to those who inherit, and one does not inherit the husband of one's wife's sister).

Abaye challenged Rav Yosef's ruling however - because he argued, maybe Rav Yehudah was referring, not to Rebbi Yossi in the Mishnah, who is Machshir Giso, but to Rebbi Yossi in the Beraisa, who disqualifies him.

We repudiate Abaye's Kashya however, on the basis of Shmuel, who with regard to Rebbi Yossi's ruling in the Beraisa declared 'K'gon Ana u'Pinchas', who - besides being brothers-in-law, were also (half) brothers, implying that that was why Rebbi Yossi disqualified them, but other brothers-in-law would be eligible to testify on each other's behalf.

We reject this proof however - since we cannot prove that Shmuel disqualified him on those grounds only. Perhaps he meant that Rebbi Yossi would disqualify them on the basis of their being brothers-in-law only.

When Rav Yosef advised the recipient of the Sh'tar Matanah to claim with the Sh'tar using Eidei Mesirah (like Rebbi Elazar, who holds 'Eidei Mesirah Karsi' even when there were no Eidei Chasimah) - Abaye argued that Eidei Mesirah are only valid in a case where the Sh'tar merely lacks Eidei Chasimah, but not where it contains Pasul witnesses, which the Chachamim refer to as 'Mezuyaf mi'Tocho'.

Rav Yosef reluctantly instructed the recipient of the Matanah - to leave without the Sh'tar (and to relinquish his claim), since the Chachamim would not allow him to validate it.

According to Rebbi Yehudah in our Mishnah, if a man's daughter dies, leaving behind children, his son-in-law is still considered a relative with regard to testifying on his behalf. Rebbi Tanchum ... Amar Rav rules like Rebbi Yehudah - whereas Rava Amar Rav Nachman (as well as Rabah bar bar Chanah Amar Rebbi Yochanan) rules - that the Halachah is not like Rebbi Yehudah.

Others quote the latter's ruling in connection with Rebbi Yossi Hagelili, who explains in a Beraisa the Pasuk in Shoftim "u'Va'sa el ha'Kohanim ... asher Yih'yeh ba'Yamim ha'Heim" (which otherwise appears meaningless) to mean that - one may take one's lawsuit to the Kohen of those days, even though he had once been a relation (Karov ve'Nisrachek).

When Mar Ukva refused to accept his brothers-in-laws' lawsuit - they concluded that, despite the fact of his wife (their sister) having died, he must hold like Rebbi Yehudah, and they informed him that they had a letter from Eretz Yisrael, which declared 'Ein Halachah ke'Rebbi Yehudah'.

He answered them however that he too, was aware that they were no longer bound by their relationship, and - that he had disqualified them because they refused to accept the Beis-Din's rulings ('Lo Tzaysi Dini').