Leviticus 16 describes the ceremony that purged the Tent of Meeting of impurity. The Torah then calls on the Israelites to practice “self-denial” on the tenth day of the seventh month as a law for all time. Self-denial is associated with fasting in Isaiah 58:5 and Psalm 35:13. The Rabbis added a few more prohibitions and explicitly included the teshuvah for transgressions between human beings. These 10 days between Rosh Hashanah and Yom Kippur are designed to be the window of opportunity to engage in cheshbon nefesh (“soul searching”) and right our relationships with others and God. The Rabbis imagine that the second set of tablets was given on Yom Kippur as a reward for the teshuvah and cheshbon nefesh that the Israelites engaged in following the sin of the golden calf.
Backing up 40 days, the time Moses spends on the mountaintop (Exod. 34:28), puts us at the beginning of Elul, when the traditional preparatory period begins. (The connection between soul searching, fasting, and 40 days also appears in Christian Scripture. See Matt. 4:2 and Luke 4:2.) The climax of the worship service is to imitate the High Priest in the Temple, prostrate oneself, and repeat the ancient formula beseeching atonement. Readings include the Book of Jonah that highlights God’s desire for teshuvah and the gracious bestowal of forgiveness.
[Courtesy : Professor Shai Cherry]