Reference for Bekhorot 63:39

דמעשר מפני דבכור לא מפני

But still [the expression] in connection with a tithing animal is not free, since we can refute the analogy as we did above?<span class="x" onmousemove="('comment',' The case of a firstling being different, as it is hallowed from birth.');">²⁰</span>

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