Reference for Niddah 57:67

אמר רבינא

— Rabina replied, Because it may be said: Most beasts bear young that are exempt from the law of the firstling<span class="x" onmousemove="('comment',' Since each beast can only bear one firstling. ');">⁵⁹</span>

Jastrow

Jastrow

Jastrow

Jastrow