In the first Mishna of Massekhet Berakhot (daf, 2), Rabban Gamliel taught that many commandments that are supposed to be completed by midnight, can really be done until dawn. The Gemara on today’s daf notes that the commandment to eat the Passover sacrifice is not included in his list, indicating that Rabban Gamliel believes that it cannot wait until dawn and must be completed by midnight.
Rav Yosef explains that in fact there is a difference of opinion between the tannaim regarding this point. Rabbi Elazar ben Azarya agrees with Rabban Gamliel that the sacrifice must be eaten by midnight while Rabbi Akiva believes that it can be eaten until dawn. Rabbi Abba explains that they differ with regard to when the period of “haste” that represented redemption took place – when the Egyptians hurried to their homes at night to encourage them to leave, or when the Israelites hurried to leave during the day. All agree, however, that permission for redemption was given at night and that the redemption itself took place during the day.
In his Ein Ayah, Rav Kook explains that here are two separate elements to the transition from slavery to freedom. First, the slave acquires a personal sense of freedom and becomes master of his own fate. Second, he becomes free in the eyes of others, i.e., he is perceived by those surrounding him as a free man and has the potential to influence them. With regard to the children of Israel, the first element enabled them to receive the Torah and elevate themselves with the fulfillment of God’s commandments. The second element provided Israel with the opportunity to become a “light unto the nations.” Therefore, the redemption was divided into two stages. The first stage, in which they acquired private, personal freedom, took place at night; the second stage, which drew the attention of the world to the miracle of the Exodus, took place during the day.