וְהָיְתָ֥ה לָכֶ֖ם לְחֻקַּ֣ת עוֹלָ֑ם בַּחֹ֣דֶשׁ הַ֠שְּׁבִיעִי בֶּֽעָשׂ֨וֹר לַחֹ֜דֶשׁ תְּעַנּ֣וּ אֶת־נַפְשֹֽׁתֵיכֶ֗ם וְכָל־מְלָאכָה֙ לֹ֣א תַעֲשׂ֔וּ הָֽאֶזְרָ֔ח וְהַגֵּ֖ר הַגָּ֥ר בְּתוֹכְכֶֽם׃
E isso vos será por estatuto perpétuo: No sétimo mês, no décimo dia do mês, afligireis vossas almas e não fareis nenhum trabalho, nem o nativo nem o estrangeiro que peregrina entre vós.
Mishneh Torah, Rest
Another positive command concerning Yom Kippur requires us to abstain from eating or drinking on that day, as it is written: "You shall afflict yourselves" (Leviticus 16:29). According to tradition, self-affliction signifies fasting. Whoever fasts on Yom Kippur fulfills a positive command, and whoever eats or drinks on it breaks a positive command and transgresses a negative command, as it is written: "Whoever will not abstain and fast on that day shall be cut off" (Leviticus 23:29). Since the verse [explicitly] punished one who did not afflict himself [with] the punishment of excision, we have [also] learned that we are warned about eating and drinking on it. And anyone who eats or drinks on it inadvertently must bring a fixed sin-offering.
Mishneh Torah, Positive Mitzvot
To fast on the tenth day of that month, as it is said, “On the tenth day of the month, ye shall afflict your souls” (Lev. 16:27).
Mishneh Torah, Negative Mitzvot
Not to do work on the Day of Atonement, as it is said concerning it, “Ye shall do no manner of work” (Lev. 23:31).