Positive Mitzvah 162
Resting on Shavuot
Leviticus 23:21 "And you shall proclaim on this very same day that it be a holy gathering"
We are commanded to regard the holiday of Shavuot as a sacred holiday. On this holiday, we must stop all our weekday activity (see Negative Mitzvah 325).
Negative Mitzvah 325
It is forbidden to work on Shavuot
Leviticus 23:21 "You shall do no manner of servile work"
This Negative Mitzvah applies to the festival of Shavuot.
We are commanded not to do work on this holiday.
Outside of Eretz Yisrael, this Negative Mitzvah applies to the second day, as well, which is still Yom-Tov.
Positive Mitzvah 163
Resting on Rosh HaShanah
Leviticus 23:24 "In the seventh month, on the first day of that month, there shall be a day of rest for you"
We are commanded to rest on the first day of the seventh month, the first of Tishrei, which is the holiday of Rosh HaShanah (see Negative Mitzvah 326).
Negative Mitzvah 326
It is forbidden to work on Rosh HaShanah
Leviticus 23:24-25 "In the seventh month on the first day of the month...you shall do no servile work"
We are commanded not to do work on Rosh HaShanah.
Our Sages declared that this holiday should be celebrated for two days, even in Eretz Yisrael.