Reference for Bekhorot 111:4

(שמות כב, כט) כן תעשה אם אינו ענין לבכור דלא איתיה בעשייה דברחם קדוש תנהו ענין למעשר בהמה

- Scripture says: Thus thou shalt do.<span class="x" onmousemove="('comment',' The words 'Thou shalt do' means the act of consecration which of course cannot apply to a first-born, since the latter is holy from birth and no special act of dedication is necessary.');">³</span>

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