Reference for Chullin 261:41

שלא תטול תפארתו ממנו

and R'Levi said: 'After thee' implies that which is forgotten.<span class="x" onmousemove="('comment',' For the law of the forgotten sheaf or cluster applies only to what has been left 'after' i.e., behind one, but not to what is still in front of one; cf. Pe'ah VI, 4, and B.M. 12a');"><sup>32</sup></span>