Mishnayos Eduyos Perek 4 Mishnah 1

ביצה שנולדה ביום טוב – we are dealing with the Holy Day [that occurs] right after Shabbat, and the reason for the School of Hillel is that they say that a person should not eat it (i.e., an egg) because every egg that is born/hatched today, it was completed the day before and it is found that Shabbat is preparing for the Holy Day. And the Torah states (Exodus 16:5): “But on the sixth day, when they apportion [what they have brought in, it shall prove to be double the amount they gather each day].” But a regular “Friday” is a secular/non-holy day. One can prepare on a non-sacred day for Shabbat, and one can prepare on a non-sacred day for the Holy Day and the Holy Day is called “Shabbat,” but on a Holy Day, one cannot prepare for the Shabbat, nor can one prepare on the Sabbath for a Holy Day, and the preparation of an egg, even though it is in the hands of Heaven, is called “preparation.”

שאור בכזית – in regards to eating, the whole world doesn’t disagrees that both {the Schools of Hillel and Shammai) agree that the minimum [prohibited amount of leaven] is an olive’s bulk, since the Biblical verse begins with leaven (Exodus 12:19): “No leaven shall be found in your houses [for seven days]…” and it (i.e., the verse) concludes (ibid.): “For whoever eats what is leavened,” to inform you that leaven is equivalent to Hametz, just as the one, so is the other. But they dispute regarding getting rid of it. The School of Shammai holds that since the All-Merciful wrote concerning both “leaven and Hametz,” we learn from it that the measure of one is not the same as the measure of the other, and we don’t derive getting rid of it from [the prohibition of] eating of it. But the School of Hillel holds that we do derive getting rid of [Hametz] from [the prohibition of] eating of it.