And the 48th mitzvah is that we are commanded to bring an offering in addition [to the daily offerings1] on the tenth day of Tishrei. [This is the musaf Yom Kippur offering.]

The source of this commandment is G‑d's statement2 (exalted be He), "On the 10th of this must present a burnt-offering as an appealing fragrance to G‑d [one bull, one ram, and seven sheep]."