Reference for Bekhorot 6:16

מומין אלו בין קבועין בין עוברין פוסלין

Now, we may giant your argument as far as [the case of a firstling] with a small eye like a goose is concerned, this being a species<span class="x" onmousemove="('comment',' Birds being exempt from the law of the firstling.');">¹¹</span>

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