Reference for Bekhorot 111:18

אמר קרא תעשה בשעת עשייה מיעט הכתוב

- Said Raba: Scripture says: 'Thou shalt do', intimating that only when doing [i.e., the act of consecration] is possible<span class="x" onmousemove="('comment',' Lit., 'in the time of doing'. When dedication is appropriate, viz., after birth but not when the embryo is still in the inside of the animal.');">¹⁰</span>

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