Positive commandment · Mitzvat Aseh #41 of 613
To offer an additional sacrifice every Shabbat
להוסיף קרבן אחר בכל שבת
The verse · Bamidbar 28:9
וּבְיוֹם הַשַּׁבָּת שְׁנֵי־כְבָשִׂים בְּנֵי־שָׁנָה תְּמִימִם וּשְׁנֵי עֶשְׂרֹנִים סֹלֶת מִנְחָה בְּלוּלָה בַשֶּׁמֶן וְנִסְכּוֹ
“And on the sabbath day two lambs of the first year without blemish, and two tenth measures of flour for a meal offering, mingled with oil, and its drink offering:”
The Rambam’s words
To offer an additional sacrifice every Shabbat, as [Numbers 28:9] states: "On the Shabbat day, two lambs...."
להוסיף קרבן אחר בכל שבת, שנאמר: "וּבְיוֹם הַשַּׁבָּת שְׁנֵי כְּבָשִׂים" (במדבר כח, ט).
Why · Sefer HaChinuch #402
Additional sacrifice of Shabbat
“From the roots of the commandment is like the matter that we wrote above regarding the sacrifice (Sefer HaChinukh 95) — that a man is acted upon according to his deeds.”
Where in the Mishneh Torah
Hilchot Daily Offerings and Additional Offerings הלכות תמידים ומוספין