Positive commandment · Mitzvat Aseh #40 of 613
For the High Priest to offer a meal offering each day
להקריב כהן גדול מנחה בכל יום
The verse · Vayikra 6:13
זֶה קׇרְבַּן אַהֲרֹן וּבָנָיו אֲשֶׁר־יַקְרִיבוּ לַה׳ בְּיוֹם הִמָּשַׁח אֹתוֹ עֲשִׂירִת הָאֵפָה סֹלֶת מִנְחָה תָּמִיד מַחֲצִיתָהּ בַּבֹּקֶר וּמַחֲצִיתָהּ בָּעָרֶב
“This is the offering of Aharon and of his sons, which they shall offer to the Lord on the day when he is anointed; the tenth part of an efa of fine flour for a meal offering perpetual, half of it in the morning, and half of it at night.”
The Rambam’s words
For the High Priest to offer a meal offering each day, as [Leviticus 6:13] states: "This is the sacrifice of Aaron and his descendants."
להקריב כהן גדול מנחה בכל יום, שנאמר: "זֶה קָרְבַּן אַהֲרֹן וּבָנָיו" (ויקרא ו, יג).
Why · Sefer HaChinuch #136
Daily meal-offering of the high priest
“It is from the roots of the commandment [that it is] because the high priest is the agent between Israel and their Father in Heaven — meaning to say, that he is the one that carries prayer to Him for their sake; and through his prayers and the act of his sacrifices, they are atoned.”
Who & when
“And it is practiced at the time of the [Temple] by the high priest.”
Where in the Mishneh Torah
Hilchot Daily Offerings and Additional Offerings הלכות תמידים ומוספין