Rav Chisda's father or father-in-law?

In today’s daf, Sanhedrin 8a, we encounter Rav Nachman, the son of Rav Chisda. Rav Chisda was a quasi-second, mostly third-generation Amora, and so his son is one stepped generation down. He asks a question to Rav Nachman bar Yaakov, also quasi-second, mostly third-generation. This is plain Rav Nachman, but we need to qualify it with the patronymic because there is already a “Nachman” in the picture making it unclear. RNbRC asks this question to RNbY in a way that shows subservience — יְלַמְּדֵנוּ רַבֵּינוּ, let our teacher instruct us. Thus:

תַּשְׁלוּמֵי כֶּפֶל כּוּ׳. שְׁלַח לֵיהּ רַב נַחְמָן בַּר רַב חִסְדָּא לְרַב נַחְמָן בַּר יַעֲקֹב: יְלַמְּדֵנוּ רַבֵּינוּ, דִּינֵי קְנָסוֹת בְּכַמָּה? מַאי קָמִיבַּעְיָא לֵיהּ? הָא אֲנַן תְּנַן בִּשְׁלֹשָׁה! אֶלָּא יָחִיד מוּמְחֶה קָמִיבַּעְיָא לֵיהּ, דְּאֵין דִּינֵי קְנָסוֹת אוֹ לָא?

§ The mishna teaches: Cases involving payment of double the principal must be adjudicated by a court of three judges. Rav Naḥman bar Rav Ḥisda sent an inquiry to Rav Naḥman bar Ya’akov: Let our teacher instruct us: With regard to cases involving laws of fines, by how many judges must such cases be adjudicated? The Gemara asks: What is the dilemma he is raising? Didn’t we learn in the mishna that such cases are judged by three judges? Rather, Rav Naḥman bar Rav Ḥisda is raising a dilemma with regard to a single expert judge: May he adjudicate cases involving laws of fines by himself or not?

אֲמַר לֵיהּ: תְּנֵיתוּהָ, תַּשְׁלוּמֵי כֶּפֶל וְתַשְׁלוּמֵי אַרְבָּעָה וַחֲמִשָּׁה בִּשְׁלֹשָׁה. מַאי שְׁלֹשָׁה? אִילֵּימָא שְׁלֹשָׁה הֶדְיוֹטוֹת, הָאָמַר אֲבוּהּ דַּאֲבוּךְ מִשְּׁמֵיהּ דְּרַב: אֲפִילּוּ עֲשָׂרָה וְהֵן הֶדְיוֹטוֹת פְּסוּלִין לְדִינֵי קְנָסוֹת! אֶלָּא מוּמְחִין, וְקָאָמַר שְׁלֹשָׁה.

Rav Naḥman bar Ya’akov said to him: You already learned this in the mishna: Cases involving payment of double the principal and payment of four or five times the principal must be adjudicated by three judges. What is meant by three? If we say it means three non-ordained lay judges, didn’t your father’s father say in the name of Rav: Even if there are ten judges, if they are lay judges they are unfit for adjudicating cases involving laws of fines? Rather, the mishna is discussing expert judges, and it says that three are necessary. Therefore, a single expert judge may not adjudicate such cases.

We see that Rav Nachman bar Yaakov speaks to Rav Nachman bar Rav Chisda, referring to אֲבוּהּ דַּאֲבוּךְ מִשְּׁמֵיהּ דְּרַב, “your father’s father say in the name of Rav”. The father would be the famous Rav Chisda, and his father would be The Father of Rav Chisda. We don’t have a name for him, and I am unaware of him prominently speaking any halachot anywhere, or him being a student of Rav.

This strangeness can be addressed if we look at manuscripts. There, we see it in the Yad HaRav Herzog manuscript as אבוה דאימך, “your mother’s father”.

In Toledot Tannaim vaAmoraim, Rav Aharon Hyman addresses this sugya at the top of the entry for Rav Chisda, proposing just such an emendation.

Based on the Chisda family tree, this mother’s father — that is, Rav Chisda’s father-in-law, was Rav Chanan bar Rava. You can read all about him in Toledot Tannaim vaAmoraim. He was Rav’s son-in-law, so keep that in mind as he is citing Rav.

Another interesting point as we went through this sugya. The Talmudic Narrator rejects an initial understanding of the question posed to Rav Nachman, changing it to be whether a yachid mumcheh could rule in fines, not just money. There is good support for this based on personality. Just the other day, at the top of Sanhedrin 5a, it was this same Rav Nachman bar Yaakov who said that he was a yachid mumcheh who could judge monetary cases alone.

וְאִם הָיָה מוּמְחֶה לְרַבִּים, דָּן אֲפִילּוּ יְחִידִי. אָמַר רַב נַחְמָן: כְּגוֹן אֲנָא דָּן דִּינֵי מָמוֹנוֹת בִּיחִידִי. וְכֵן אָמַר רַבִּי חִיָּיא: כְּגוֹן אֲנָא דָּן דִּינֵי מָמוֹנוֹת בִּיחִידִי.

But if one was a judge accepted as an expert for the public, then he may judge cases even as the lone judge. Rav Naḥman said: One such as I may judge cases of monetary law as the lone judge. And similarly, Rabbi Ḥiyya said: One such as I may judge cases of monetary law as the lone judge.