Reference for Chullin 164:42

אלא לאו סומכוס היא

Is not the warning [with regard to each] dubious?<span class="x" onmousemove="('comment',' For R. Judah is in doubt as to which thigh the prohibition applies; hence the warning with regard to the eating of each of them is dubious, for each one may be the one that is permitted, consequently he should be exempt entirely from stripes.');">¹⁹</span>

Jastrow