The Oral Talmud with Benay Lappe and Dan Libenson Episode 153

There was a certain person who came before Rabbi Ami and said to him: In the Torah scroll that I wrote for so-and-so, I did not write the mentions of God’s name with the proper intention. Rabbi Ami said to him: This Torah scroll is in whose possession? He said to him: in the buyer’s possession. He said to him: You are deemed credible to cause the loss of your wage. But you are not deemed credible to cause a loss of the Torah scroll.

There was an incident involving one who came before Rabbi Yehuda and said to him: I converted in private. Rabbi Yehuda said to him: Do you have witnesses? He said to him: No. Do you have children? He said to him: Yes. He said to him: You are deemed credible to render yourself unfit, but you are not deemed credible to render your children unfit.

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.