Reference for Bekhorot 51:14

אלא לאו התירו מומחה איכא בינייהו דתנא קמא סבר

Indeed the Sages clearly said: He shall place it in the window, as perhaps there is hope [of being able to use it].<span class="x" onmousemove="('comment',' If he should slaughter it as it is stated in the next passage.');">⁹</span>

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