Reference for Zevachim 193:2
<big><strong>גמ׳</strong></big> מאי טעמא דר"ט דאמר קרא (דברים טז, ז) ופנית בבקר והלכת לאהלך הכתוב עשאו לכולן בקר אחד
<big><b>GEMARA: </b></big>What is R'Tarfon's reason? - Because Scripture saith, And thou shalt turn in the morning, and go unto thy tents:<span class="x" onmousemove="('comment',' Deut. XVI,7. This means that the Israelite could return home on the morning after the festival.');"><sup>3</sup></span> the Writ treats the whole [of the festival] as one morning.<span class="x" onmousemove="('comment',' I.e., as one day. Since the reason for scouring and rinsing is that what is absorbed of the meat in the pot becomes nothar, it follows that it cannot become nothar from the beginning until the end of a festival, as it is all counted as one day.');"><sup>4</sup></span>