Resting on the First Day of Sukkot
"On the first day [of Sukkot] there shall be a holy convocation"—Leviticus 23:35.
We sanctify the fifteenth of Tishrei, the first day of Sukkot, by resting on that day—defined as abstaining from any creative work, with the exception of work needed for food purposes.
Working on the First Day of Sukkot
"...You shall do no servile work"—Leviticus 23:35.
It is forbidden to engage in creative work—with the exception of work needed for food purposes—on the fifteenth of Tishrei, the first day of Sukkot.
Resting on Shemini Atzeret
"On the eighth day, there shall be a holy convocation for you"—Leviticus 23:36.
We sanctify Shemini Atzeret, the twenty-second of Tishrei, the eighth day from the first day of Sukkot, by resting on that day—defined as abstaining from any creative work, with the exception of work needed for food purposes.
Working on Shemini Atzeret
"...You shall do no servile work"—Leviticus 23:36.
It is forbidden to engage in creative work—with the exception of work needed for food purposes—on Shemini Atzeret, the twenty-second of Tishrei.
Eating Chametz after Noon of the Fourteenth of Nissan
"You shall eat no leavened bread upon it"—Deuteronomy 16:3.
We are forbidden to eat chametz (leavened foods) after midday of the fourteenth of Nissan. As the Torah says, "You shall eat no leavened bread upon it"—"it" referring to the Paschal Offering, which was offered after midday on the eve of Passover.
(The Sages extended this prohibition to include a time period before midday, to prevent anyone from inadvertently consuming chametz after midday, when it is biblically forbidden.)