Avodah Zarah 49A

שאם נטע והבריך והרכיב ⁠— מותר.

that if one planted an orla nut, or sank the shoot of an orla tree into the ground, or grafted an orla tree, that which grows as a result is permitted.

וכי תימא, שני ליה לרבי יוסי בין שאר איסורין לעבודה זרה, ומי שני ליה? והתניא: שדה שנזדבלה בזבל עבודה זרה, וכן פרה שנתפטמה בכרשיני עבודה זרה, תני חדא: שדה תזרע, פרה תשחט, ותניא אידך: שדה תבור, ופרה תרזה.

And if you would say that this is not difficult, as R' Yosei distinguishes between items that are forbidden due to other prohibitions and items that are forbidden due to idol worship, does he indeed distinguish in this manner? But isn’t it taught that with regard to a field that was fertilized with dung that came from an animal used in idol worship, and similarly, with regard to a cow that was fattened with vetches used in idol worship, there are opposing opinions: It is taught in one baraita that the field may be sown in the normal manner and the cow may be slaughtered and eaten, and it is taught in another baraita that the field should be left fallow, and the cow should be made lean, until the effects of the dung or vetches have passed.

מאי לאו הא רבי יוסי, והא רבנן? לא, הא רבי אליעזר, והא רבנן.

What, is it not that this baraita that rules leniently is in accordance with the opinion of R' Yosei, who holds that when both permitted and forbidden items contribute to a result, the result is permitted, and that baraita that rules stringently is in accordance with the opinion of the Rabbis? If so, it is clear that R' Yosei does not distinguish between other prohibitions and idol worship, as in this case of idol worship he still permits the result of permitted and forbidden causes. The Talmud answers: No, these baraitot do not reflect the opinions of R' Yosei and the Rabbis. Rather, this baraita is in accordance with the opinion of R' Eliezer, and that baraita is in accordance with the opinion of the Rabbis, who disagree with him.