Reference for Menachot 12:19

וכיון דקרא סתמא כתיב בה מה לי שמאל ומה לי שאר הפסולין

that is, from the place where the feet of the non-priest may stand.<span class="x" onmousemove="('comment',' I.e., the rite of taking the handful from the meal-offering may be performed anywhere in the Temple court, even in the space of eleven cubits, on the east side of the court, where laymen were allowed to stand (cf. Yoma 16b) .');">²⁴</span> Ben Bathyra says, Whence do we know that if he took the handful with the left hand, he should put it back again and then take it out with the right hand?

Jastrow