Reference for Pesachim 166:11

חל ט"ז וכו': ואמאי ניתי עשה וידחי לא תעשה

For Rab Judah said in Samuel's name: The inner one which is near the bone is forbidden, and a person is liable on its account [to flagellation]; the other which is near the flesh is forbidden, but a person is not liable on its account.<span class="x" onmousemove="('comment',' It is forbidden by Rabbinical law only. The reasoning in the preceding note applies here too.');">¹⁰</span> IF THE SIXTEENTH FELL etc. Yet why so?

Jastrow