404. Extra Special: The obligation to bring additional offerings on Shavuos
On the day you bring your first fruits, when you bring the new flour offering to God, your Feast of Weeks… (Numbers 28:26)
We are commanded to bring the additional Musaf offering on Shavuos. As we said before, in Mitzvos #299 and #402, the reason for this mitzvah is to recognize the extra significance of the day. Nowadays, in the absence of the Temple, we have the extra Musaf Amidah as part of the holiday prayer service.
This mitzvah applies when the Temple service is in effect. In the Talmud, it is discussed in tractate Menachos on pages 49a-b. It is codified in the Mishneh Torah in Hilchos Temidin U’Musafin. This mitzvah is #45 of the 248 positive mitzvos in the Rambam’s Sefer HaMitzvos.