Reference for Sukkah 66:6

ואין ממעטין ביו"ט: הא עבר ולקטן מאי כשר דאשחור אימת אילימא דאשחור מאתמול דחוי מעיקרא הוא תפשוט מינה דחוי מעיקרא דלא הוי דחוי

But one may not reduce them [the berries] on Yom Tov. But if he transgressed and did pluck them it is valid. But then, when did it become black? If you will say that it became black from the previous day, then it is a case of "set aside" from the very outset. Deduce from here that something that is "set aside" from the very outset is not [permanently] set aside?

Jastrow