Reference for Pesachim 240:4

הפסח אחר חצות מטמא את הידים וכו': אלמא מחצות ה"ל נותר מאן תנא

Abaye was sitting [at the Passover meal] before Rabbah. Seeing him dozing he remarked to him, 'You, sir, are sleeping.'<span class="x" onmousemove="('comment',' This happened while he was eating the unleavened bread at the end of the meal, and Abaye meant that he might not continue now.');"><sup>3</sup></span>