Reference for Avodah Zarah 75:11

לא צריכא דאי לא הפך הוה בשיל בתרתי שעי והשתא קא בשיל בחדא שעתא מהו דתימא קרובי בישולא מילתא היא קמ"ל

No; it is necessary in a case where it would have taken two hours to cook if he had not turned it over, but now it was cooked in one hour. What might you have said? That hastening the process of cooking is a matter which is taken into consideration; hence he informs us [that it is not].

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