Study Pesachim folio 11B with parallel Hebrew-English text, traditional commentary, and modern study tools. Free access to Babylonian Talmud online.
על ממונו, אמרינן: אי שרית ליה במקום שאין עושין בו מום — אתי למעבד במקום שעושין בו מום.
about his property, as the priest who is watching the firstborn wants to slaughter it before it dies, as if it dies, eating it would be prohibited. Therefore, we say: If you permit him to let blood in a place that does not cause a blemish in the animal, he will come to do so in a place that causes a blemish in it, to save his animal.
ורבנן — כל שכן דאי לא שרית ליה כלל אתי למעבד.
And the Rabbis respond that if that is the case, all the more so should it be permitted to let blood in a manner that will not cause a blemish, for if you do not permit him to take any steps to save the animal at all, he will come to act in a prohibited manner and cause a blemish. If there is a legitimate alternative, he will not cause a blemish in the firstborn.
ומי אמרינן לרבי יהודה אדם בהול על ממונו? והתנן, רבי יהודה אומר: אין (מקדרין) הבהמה ביום טוב — מפני שהוא עושה חבורה, אבל מקרצפין. וחכמים אומרים: אין מקדרין, אף אין מקרצפין.
The Talmud challenges this explanation: And do we say that according to R' Yehuda a person is agitated about his property? But didn’t we learn in a Mishnah that R' Yehuda says: One may not scrape an animal on a Festival with a fine-tooth comb, because in doing so he inflicts a wound, which is prohibited on Festivals? However, one may scratch an animal with a wide-tooth comb, as this does not inflict a wound. And the Rabbis say: One may neither scrape nor even scratch, for if one were permitted to scratch an animal he might come to scrape it as well.
ותניא: איזהו קידור ואיזהו קרצוף? קידור — קטנים, ועושין חבורה. קרצוף — גדולים, ואין עושין חבורה.
And it was taught in the Tosefta: What is scraping and what is scratching? Scraping is performed with a comb with small teeth and with which one inflicts a wound. Scratching is performed with a comb that has large teeth and with which one does not inflict a wound. Apparently, R' Yehuda does not issue a decree to prohibit scratching lest one come to scrape, even though he is agitated over his property.
Text data via Sefaria: William Davidson Edition - English and William Davidson Edition - Vocalized Aramaic, CC-BY-NC; edition provenance: Koren. Display terminology has been modernized for readability.