Jáhádut neemánut

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The Sages taught in a baraita: With regard to someone who came and said: I am a convert, one might have thought that we should accept him; therefore, the verse states: “And if a convert sojourns with you in your land, you shall not oppress him” (Leviticus 19:33). The emphasis on “with you” suggests that only someone who was already presumed by you to be a valid convert should be accepted as a convert. If he came and brought witnesses to his conversion with him, from where is it derived that he is to be accepted? It is from the beginning of that verse, which states: “And if a convert sojourns with you in your land.”

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[One who was previously known to have been] a male or female non-Jew, who comes and says, “I was appropriately converted by a beit din of So-and-So," they still should not be believed to come to the congregation [get married] until the witnesses [of the beit din] come. But if you see them behaving in customs worthy in the way of Israel and they do all of the mitzvot, they are presumed to be righteous converts, in spite of the fact that there were no witnesses to bear witness about who converted them. And if this is the case, if they come to mix [marry] into Israel, do not marry them until the witnesses come, or until they are immersed before us, since they initially had a known status as idol worshippers. However, one [whose status was never known] who comes and says that she is an idol worshipper and was converted by a beit din, believe her, for the mouth that forbids [and admits, “I am an idol worshipper” when she didn’t have to] is the mouth that permits [and says “but I was converted by a beit din.”]. And the Rambam writes that this ruling only applied in former days, and even then, only in the land of Israel, but outside the land one needs to bring evidence before he can marry an Israelite - because [the Sages] enhanced the strictures when it came to lineages [in Jewish communities outside Israel].

We immerse a minor who seeks to convert based upon the guidance of the court. For it is an advantage for a person [to convert]. When a pregnant woman converts and immerses herself, her child does not require immersion.
When [a convert] immerses himself alone and converts alone - or even if he does this in the presence of two persons - his conversion is not valid. If he comes and says: "I converted in the court of so-and-so and they had me immerse," his word is not accepted with regard to license to marry among the Jewish people unless he brings witnesses [who testify to the truth of his statements].

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