Reference for Bekhorot 77:20

למאי נ"מ למימעל בפדיונו

Provided that the cure is administered at three<span class="x" onmousemove="('comment',' That it is examined for example, to-day and at the end of twenty-six and a half days, then further at the end of twenty-six and a half days and subsequently at the end of the period of twenty-seven days. There is usually a change at these three particular periods, and consequently if he did not examine the animal at these specific times, then we cannot declare that the animal had a permanent blemish. Tosaf, explains it as meaning that the examination must take place at the commencement of the eighty days, at the conclusion of the period and in the middle, a three-fold examination.');">¹¹</span>

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