Mishnayos Sanhedrin Perek 3 Mishnah 4

And these are the ones disqualified from bearing witness or from serving as judges due to their status as relatives of one of the litigants or of each other: One’s brother, and his paternal uncle, and his maternal uncle, and his sister’s husband, and the husband of his paternal aunt, and the husband of his maternal aunt, and his mother’s husband, and his father-in-law, and his brother-in-law, i.e., the husband of his wife’s sister. They themselves, all of these people, and also their sons, and their sons-in-law are considered relatives. And his stepson alone is disqualified, but not his stepson’s sons or sons-in-law. Rabbi Yosei says: This aforementioned halakha is Rabbi Akiva’s version of the mishna. But the initial version of the mishna reads as follows: His uncle and the son of his uncle, and anyone who is fit to inherit from him. Only paternal relatives, who are fit to inherit from him, are disqualified; maternal relatives, who do not inherit from him, are not disqualified from bearing witness about him or from adjudicating his case. And the halakha disqualifying a relative from bearing witness or serving as a judge is referring to anyone who is related to him at the time of the trial. If one was once a relative and became unrelated by the time of the trial, e.g., he married the daughter of one of the litigants, but she died or they were divorced, in this case he is fit. Rabbi Yehuda says: Even if his daughter died but her husband, the former son-in-law, has children from her, he is still considered a relative; the children cause them to remain related.

וְאֵלּוּ הֵן הַקְּרוֹבִין, אָבִיו וְאָחִיו וַאֲחִי אָבִיו וַאֲחִי אִמּוֹ וּבַעַל אֲחוֹתוֹ וּבַעַל אֲחוֹת אָבִיו וּבַעַל אֲחוֹת אִמּוֹ וּבַעַל אִמּוֹ וְחָמִיו וְגִיסוֹ, הֵן וּבְנֵיהֶן וְחַתְנֵיהֶן, וְחוֹרְגוֹ לְבַדּוֹ. אָמַר רַבִּי יוֹסֵי, זוֹ מִשְׁנַת רַבִּי עֲקִיבָא. אֲבָל מִשְׁנָה רִאשׁוֹנָה, דּוֹדוֹ וּבֶן דּוֹדוֹ. וְכָל הָרָאוּי לְיָרְשׁוֹ, וְכָל הַקָּרוֹב לוֹ בְּאוֹתָהּ שָׁעָה. הָיָה קָרוֹב וְנִתְרַחֵק, הֲרֵי זֶה כָּשֵׁר. רַבִּי יְהוּדָה אוֹמֵר, אֲפִלּוּ מֵתָה בִתּוֹ וְיֶשׁ לוֹ בָנִים מִמֶּנָּה, הֲרֵי זֶה קָרוֹב: