תָּנוּ רַבָּנַן: ״וּשְׁפַטְתֶּם צֶדֶק בֵּין אִישׁ וּבֵין אָחִיו וּבֵין גֵּרוֹ״, מִכָּאן אָמַר רַבִּי יְהוּדָה: גֵּר שֶׁנִּתְגַּיֵּיר בְּבֵית דִּין — הֲרֵי זֶה גֵּר, בֵּינוֹ לְבֵין עַצְמוֹ — אֵינוֹ גֵּר. מַעֲשֶׂה בְּאֶחָד שֶׁבָּא לִפְנֵי רַבִּי יְהוּדָה, וְאָמַר לוֹ: נִתְגַּיַּירְתִּי בֵּינִי לְבֵין עַצְמִי. אָמַר לוֹ רַבִּי יְהוּדָה: יֵשׁ לְךָ עֵדִים? אָמַר לוֹ: לָאו. יֵשׁ לְךָ בָּנִים? אָמַר לוֹ: הֵן. אָמַר לוֹ: נֶאֱמָן אַתָּה לִפְסוֹל אֶת עַצְמְךָ, וְאִי אַתָּה נֶאֱמָן לִפְסוֹל אֶת בָּנֶיךָ. [וּמִי] אָמַר רַבִּי יְהוּדָה אַבָּנִים לָא מְהֵימַן? וְהָתַנְיָא: ״יַכִּיר״ — יַכִּירֶנּוּ לַאֲחֵרִים. מִכָּאן אָמַר רַבִּי יְהוּדָה: נֶאֱמָן אָדָם לוֹמַר ״זֶה בְּנִי בְּכוֹר״, וּכְשֵׁם שֶׁנֶּאֱמָן לוֹמַר ״זֶה בְּנִי בְּכוֹר״, כָּךְ נֶאֱמָן לוֹמַר: ״בְּנִי זֶה בֶּן גְּרוּשָׁה הוּא״, אוֹ ״בֶּן חֲלוּצָה הוּא״. וַחֲכָמִים אוֹמְרִים: אֵינוֹ נֶאֱמָן! אָמַר רַב נַחְמָן בַּר יִצְחָק, הָכִי קָאָמַר לֵיהּ: לִדְבָרֶיךָ גּוֹי אַתָּה, וְאֵין עֵדוּת לְגוֹי. רָבִינָא אָמַר, הָכִי קָאָמַר לֵיהּ: יֵשׁ לְךָ בָּנִים? הֵן. יֵשׁ לְךָ בְּנֵי בָנִים? הֵן. אָמַר לוֹ: נֶאֱמָן אַתָּה לִפְסוֹל בָּנֶיךָ, וְאִי אַתָּה נֶאֱמָן לִפְסוֹל בְּנֵי בָנֶיךָ.
The Sages taught: The verse states that Moses charged the judges of a court: “And judge righteously between a man and his brother, and the convert with him” (Deuteronomy 1:16). From here, based on the mention of a convert in the context of judgment in a court, Rabbi Yehuda said: A potential convert who converts in a court is a valid convert. However, if he converts in private, he is not a convert. The Gemara relates: There was an incident involving one who was presumed to be Jewish who came before Rabbi Yehuda and said to him: I converted in private, and therefore I am not actually Jewish. Rabbi Yehuda said to him: Do you have witnesses to support your claim? He said to him: No. Rabbi Yehuda asked: Do you have children? He said to him: Yes. Rabbi Yehuda said to him: You are deemed credible in order to render yourself unfit to marry a Jewish woman by claiming that you are a gentile, but you are not deemed credible in order to render your children unfit. The Gemara asks: But did Rabbi Yehuda actually say that with regard to his children, he is not deemed credible? . . . From here Rabbi Yehuda said: A man is deemed credible to say: This is my firstborn son, Rav Naḥman bar Yitzḥak said that this is what Rabbi Yehuda said to him: According to your statement you are a gentile, and there is no testimony for a gentile, as a gentile is a disqualified witness. Consequently, you cannot testify about the status of your children and render them unfit.
§ The Sages taught in a baraita: With regard to a potential convert who comes to a court in order to convert, at the present time, when the Jews are in exile, the judges of the court say to him: What did you see that motivated you to come to convert? Don’t you know that the Jewish people at the present time are anguished, suppressed, despised, and harassed, and hardships are frequently visited upon them? If he says: I know, and although I am unworthy of joining the Jewish people and sharing in their sorrow, I nevertheless desire to do so, then the court accepts him immediately to begin the conversion process. And the judges of the court inform him of some of the lenient mitzvot and some of the stringent mitzvot, and they inform him of the sin of neglecting the mitzva to allow the poor to take gleanings, forgotten sheaves, and produce in the corner of one’s field, and about the poor man’s tithe. And they inform him of the punishment for transgressing the mitzvot, as follows: They say to him: Be aware that before you came to this status and converted, had you eaten forbidden fat, you would not be punished by karet, and had you profaned Shabbat, you would not be punished by stoning, since these prohibitions do not apply to gentiles. But now, once converted, if you have eaten forbidden fat you are punished by karet, and if you have profaned Shabbat, you are punished by stoning.
they are not able to receive either an abundance of good nor an abundance of calamities, since the primary place for reward and punishment is in the World-to-Come. And they do not overwhelm him with threats, and they are not exacting with him about the details of the mitzvot. If he accepts upon himself all of these ramifications, then they circumcise him immediately. . . .When he is healed from the circumcision, they immerse him immediately, and two Torah scholars stand over him at the time of his immersion and inform him of some of the lenient mitzvot and some of the stringent mitzvot. Once he has immersed and emerged, he is like a born Jew in every sense. . . . The Master said in the baraita: With regard to a potential convert who comes to a court in order to convert, the judges of the court say to him: What did you see that motivated you to come to convert? And they inform him of some of the lenient mitzvot and some of the stringent mitzvot. The Gemara asks: What is the reason to say this to him? It is so that if he is going to withdraw from the conversion process, let him withdraw already at this stage. He should not be convinced to continue, as Rabbi Ḥelbo said: Converts are as harmful to the Jewish people as a leprous scab [sappaḥat] on the skin, as it is written: “And the convert shall join himself with them, and they shall cleave [venispeḥu] to the house of Jacob” (Isaiah 14:1). This alludes to the fact that the cleaving of the convert to the Jewish people is like a scab. The baraita continues: And they inform him of the sin of neglecting the mitzva to allow the poor to take gleanings, forgotten sheaves, and produce in the corner of one’s field, and about the poor man’s tithe. The Gemara asks: What is the reason to specifically mention these mitzvot? Rabbi Ḥiyya bar Abba said that Rabbi Yoḥanan said: Because a gentile is executed even on account of stealing less than the value of a peruta, since gentiles are particular about even such a small loss, and an item that a gentile steals is not subject to being returned, i.e., he is not obligated to return it to its owner. The baraita continues: And they inform him of the sin of neglecting the mitzva to allow the poor to take gleanings, forgotten sheaves, and produce in the corner of one’s field. And they do not overwhelm him with threats, and they are not exacting with him about the details of the mitzvot, i.e., the court should not overly dissuade the convert from converting. Rabbi Elazar said: What is the verse from which this ruling is derived? As it is written: “And when she saw that she was steadfastly minded to go with her, she left off speaking with her” (Ruth 1:18). . . . . Immediately following this dialogue, the verse states: “And when she saw that she was steadfastly minded she left off speaking with her” (Ruth 1:18). Once Naomi saw Ruth’s resolve to convert, she desisted from her attempts to dissuade her.