Chapter 16 details the service procedure on Yom Kippur. The Mishnah explains that the service must be performed in the exact order listed in the Torah or it is deemed invalid (Mishnah Yoma 5:7). There is something else unique in the chapter. When other holidays are mentioned in the Torah, the holiday itself is mentioned first and then the specific mitzvah for the day. In this chapter, the first thing mentioned is the death of Aaron’s two sons from six chapters ago, and then the service and then, in the summery, the connection between Yom Kippur and the service and then the commandment that it is Shabbat Shabbaton and a day for self-sacrifice.

What’s the connection between Yom Kippur and the death of Aaron’s sons? Perhaps it has to do with the wording of the reason for their death:

“God spoke to Moses after the death of the two sons of Aaron who died when they drew too close to the presence of God” (verse 1).

וַיְדַבֵּר ה' אֶל־מֹשֶׁה אַחֲרֵי מוֹת שְׁנֵי בְנֵי־אַהֲרֹן בְּקָרְבָתָם לִפְנֵי־ה' וַיָּמֻתוּ׃

In the four times that their death is mentioned in the Torah, this is the only time it does not say they brought a foreign fire. Some commentators explain that this meant that Nadav and Avihu died because they tried to get too close to God—either by entering the Holy of Holies or by bringing a sacrifice that was not ordained. In other words they had pure intentions, but their execution was wrong. God explains to Aaron and the people that there is a specific way that the nation can utilize the Mishkan to enact forgiveness. It is through this exact ceremony that must be performed in this exact order that one can achieve forgiveness. Aaron’s sons attempted to do something else, and God needed to remind the people that the Mishkan was not some temple with an anything goes ruleset.

But the second unique part of the chapter is the more important lesson. Yes, one needs to do this exact service to gain forgiveness. But, God says, there is another way:

“For on this day atonement shall be made for you to purify you of all your sins; you shall be pure before God / It shall be a sabbath of complete rest for you, and you shall practice self-denial; it is a law for all time” (verses 30–31).

כִּי בַיּוֹם הַזֶּה יְכַפֵּר עֲלֵיכֶם לְטַהֵר אֶתְכֶם מִכָּל־חַטֹּאתֵיכֶם לִפְנֵי ה' תִּטְהָרוּ׃

שַׁבַּת שַׁבָּתוֹן הִוא לָכֶם וְעִנִּיתֶם אֶת־נַפְשֹׁתֵיכֶם חֻקַּת עוֹלָם׃

In this not so subtle way God is explaining that each and every person has the ability to gain forgiveness on Yom Kippur without the service. That is why this verse appears after the declaration of Yom Kippur like every other holiday, but the Mishkan service does not.