Reference for Chullin 148:15

מחלוקת בבן ט' חי והלך ר"מ לשיטתו

R'Judah says: One need only peel off the [fat at the] top<span class="x" onmousemove="('comment',' But the remaining fat in the region of the nerve is permitted.');">⁵</span>

Jastrow