The Hebrews were to humble themselves before the Lord. This is an act of submission, self-denial, and self-mortification. This may be accompanied by prayer and fasting (see Leviticus 16:29–31). This command is repeated three times in this pericope, highlighting the essential responses of the people (Leviticus 23:27; Leviticus 23:29; Leviticus 23:32). Additionally, no work may be done on these days. Ross adds, There will be no spiritual renewal for the people if they do not prepare their hearts for it.
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28 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.