Reference for Bekhorot 42:27

אמר רב

What is the ruling, however, where [an Israelite] purchases [an animal] from an Israelite? - Said Rab: It is surely a firstling, for if it had given birth, he would certainly have recommended it on this ground.<span class="x" onmousemove="('comment',' That the animal had already given birth and thus the priest had no further claim on the offspring.');">¹⁹</span>

Jastrow

Jastrow

Jastrow