Reference for Bekhorot 50:25

יבוקר

And R'Nahman answered in the name of Rabah B'Abbuha: We are dealing here with the wool of a blemished firstling [torn away while alive], which became mixed up with the wool of hullin?<span class="x" onmousemove="('comment',' Unconsecrated animals, and we are not dealing here at all, with living animals.');">¹⁵</span>

Jastrow