Reference for Temurah 49:7

ולדי קדשים בהוייתן הן קדושים

A firstling shal not sanctify.<span class="x" onmousemove="('comment',' Referring to the text (Lev. XXVII, 26) : Howbeit the firstling among the beasts which is born as a firstling unto the Lord, no man shall sanctify rufc it; the Heb. denotes equally firstborn and firstling of an animal.');">⁵</span>

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