17כָּל מִשְׁפָּחוֹת בְּחֶזְקַת כְּשֵׁרוֹת וּמֻתָּר לִשָּׂא מֵהֶן לְכַתְּחִלָּה. וְאַף עַל פִּי כֵן אִם רָאִיתָ שְׁתֵּי מִשְׁפָּחוֹת שֶׁמִּתְגָּרוֹת זוֹ בָּזוֹ תָּמִיד אוֹ רָאִיתָ מִשְׁפָּחָה שֶׁהִיא בַּעֲלַת מַצָּה וּמְרִיבָה תָּמִיד. אוֹ רָאִיתָ אִישׁ שֶׁהוּא מַרְבֶּה מְרִיבָה עִם הַכּל וְעַז פָּנִים בְּיוֹתֵר. חוֹשְׁשִׁין לָהֶן וְרָאוּי לְהִתְרַחֵק מֵהֶן שֶׁאֵלּוּ סִימָנֵי פַּסְלוּת הֵם. וְכֵן הַפּוֹסֵל אֶת אֲחֵרִים תָּמִיד. כְּגוֹן שֶׁנּוֹתֵן שֶׁמֶץ בְּמִשְׁפָּחוֹת אוֹ בִּיחִידִים וְאוֹמֵר עֲלֵיהֶן שֶׁהֵן מַמְזֵרִים. חוֹשְׁשִׁין לוֹ שֶׁמָּא מַמְזֵר הוּא. וְאִם אָמַר לָהֶן שֶׁהֵם עֲבָדִים חוֹשְׁשִׁין לוֹ שֶׁמָּא עֶבֶד הוּא. שֶׁכָּל הַפּוֹסֵל בְּמוּמוֹ פּוֹסֵל. וְכֵן כָּל מִי שֶׁיֵּשׁ בּוֹ עַזּוּת פָּנִים אוֹ אַכְזָרִיּוּת וְשׂוֹנֵא אֶת הַבְּרִיּוֹת וְאֵינוֹ גּוֹמֵל לָהֶם חֶסֶד חוֹשְׁשִׁין לוֹ בְּיוֹתֵר שֶׁמָּא גִּבְעוֹנִי הוּא. שֶׁסִּימָנֵי יִשְׂרָאֵל הָאֻמָּה הַקְּדוֹשָׁה בַּיְשָׁנִין רַחֲמָנִים וְגוֹמְלֵי חֲסָדִים. וּבַגִּבְעוֹנִים הוּא אוֹמֵר (שמואל ב כא ב) "וְהַגִּבְעֹנִים לֹא מִבְּנֵי יִשְׂרָאֵל הֵמָּה" לְפִי שֶׁהֵעֵזּוּ פְּנֵיהֶם וְלֹא נִתְפַּיְּסוּ וְלֹא רִחֲמוּ עַל בְּנֵי שָׁאוּל וְלֹא גָּמְלוּ לְיִשְׂרָאֵל חֶסֶד לִמְחל לִבְנֵי מַלְכָּם וְהֵם עָשׂוּ עִמָּהֶם חֶסֶד וְהֶחֱיוּם בַּתְּחִלָּה:
We operate under the presumption that all families are of acceptable lineage and it is permitted to marry their descendants as an initial and preferred option. Nevertheless, if you see two families continuously quarreling with each other, you see one family that is always involved with strife and controversy, or you see a person who frequently quarrels with people at large and is very insolent, we suspect [their lineage]. It is fitting to distance oneself from such people for these are disqualifying characteristics. Similarly, a person who always slurs the lineage of others, casting aspersions on the ancestry of families or individuals, claiming that they are mamzerim, we are suspicious that he himself is a mamzer. Similarly, if he calls others servants, we suspect that he is a servant. For whoever denigrates others, denigrates them with a blemish that he himself possesses. Similarly, whenever a person is characterized by insolence and cruelty, hating people and not showing kindness to them, we seriously suspect that he is a Gibeonite. For the distinguishing signs of the holy nation of Israel is that they are meek, merciful, and kind. With regard to the Gibeonites, [II Samuel 21:2] states: "The Gibeonites are not of the Jewish people." For they acted extremely brazenly and would not be appeased. They did not show mercy to the sons of [King] Saul, nor did they show kindness to the Jews to forgive the descendants of their king, while [the Jews] had shown them kindness and allowed them to live.