Reference for Chullin 137:40

דתנן

in the beast, [it ye may eat];<span class="x" onmousemove="('comment',' Deut. XIV, 6. The interpretation is, every beast in a beast, i.e., the foetus in the womb of its dam, is permitted by the slaughtering of the dam.');">²⁴</span>

Jastrow