Mishneh Torah — Positive Mitzvot מצוות עשה, Chapter 30
The full Hebrew text of Mishneh Torah, Positive Mitzvot, Chapter 30, with English translation by Maimonides (Rambam).
לְהָרִים הַדֶּשֶׁן מֵעַל הַמִּזְבֵּחַ בְּכָל יוֹם, שֶׁנֶּאֱמָר: "וְהֵרִים אֶת הַדֶּשֶׁן" (ויקרא ו, ג).
To remove the ashes from the altar, as [Leviticus 6:3] states: "And he shall remove the ashes...."