There are many laws that are unique to Shabbat meals. On today’s daf the Gemara discusses the sources of some of those halakhot.
Rav Ḥisda said: A person should always rise early on Friday in order to prepare all of the expenditures for Shabbat, as it is written with regard to the collection of the manna: “And it shall be on the sixth day, and they will prepare that which they have brought” (Shemot 16:5), indicating that the children of Israel would begin preparing the food for Shabbat immediately upon collecting the manna in the morning.
With the statement, “And it shall be,” the Torah indicates that the people should begin preparations, “they will prepare” (Shemot 16:5), immediately when the day begins. An alternative interpretation is that since they did not collect the manna at night, the Torah teaches that preparations began with its collection in the early hours of the morning (Ritva).
Apropos manna, the Gemara mentions other matters derived from it.
Rabbi Abba said: On Shabbat a person is obligated to break bread in his meal over two loaves of bread, as it is written: “And it happened on the sixth day, they collected double the bread, two omer for each one” (Shemot 16:22).
Rav Ashi said: I saw that Rav Kahana took two loaves in his hand and broke one, not both at once. He said in explanation that it is written: “They collected double the bread,” meaning that one collects and holds two loaves together, but need not break both. Rabbi Zeira would break off a piece that would suffice for his entire meal.
Ravina said to Rav Ashi: Doesn’t that appear like gluttony? Rav Ashi said to him: Since on every other day he does not do this and now he is doing so, it does not appear like gluttony.
Some commentaries explain that Rabbi Zeira would break all of the loaves that he prepared for the meal (Rashba).