The Day of Atonement – Leviticus 23:26-32; 16:1-30
The Day of Atonement is a Biblical Holy Day God appointed to make a covering for His people SIN. It pointed forward to the alternate atonement. The Book Hebrews in large part is a commentary on the Day of Atonement. In the sermon after David walks through a large part of Hebrews explaining how it’s fulfillment is found in Jesus Christ.
And the LORD spoke to Moses, saying,  “Now on the tenth day of this seventh month is the Day of Atonement. It shall be for you a time of holy convocation, and you shall afflict yourselves and present a food offering to the LORD.  And you shall not do any work on that very day, for it is a Day of Atonement, to make atonement for you before the LORD your God.  For whoever is not afflicted on that very day shall be cut off from his people.  And whoever does any work on that very day, that person I will destroy from among his people.  You shall not do any work. It is a statute forever throughout your generations in all your dwelling places.  It shall be to you a Sabbath of solemn rest, and you shall afflict yourselves. On the ninth day of the month beginning at evening, from evening to evening shall you keep your Sabbath.” (Leviticus 23:26–32 ESV)