Reference for Bekhorot 63:43

דנין גאולה מגאולה ואין דנין פדייה מגאולה

whereas the 'redemption' mentioned in connection with a firstling is not free [for interpretation].<span class="x" onmousemove="('comment',' In the first place, it is required for its own sake, to show that the animal cannot be redeemed, and secondly for the analogy between 'passing' and 'passing'.');">²⁴</span>

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