Why Sukkot Is the First Day for a Fresh Accounting of Sin

"On the first day" (Leviticus 23:40). It is the fifteenth of the month, yet Scripture says "on the first day." Rabbi Mani of Sheab and Rabbi Joshua of Sikhnin in the name of Rabbi Levi: it is like a province that owed arrears of taxes to the king, and the king went to collect them. Within ten miles the great men of the province came out and praised him, so the king remitted a third of their tax. Within five miles the leading officials of the province came out and praised him, so the king remitted a third of their tax. And when the king entered the province, all the townspeople came out and praised him, so the king said to them, "What is past is past; from here on it is a new accounting." So too Israel come on Rosh Hashanah and do repentance, and the Holy One remits a third of their sins. They come during the Ten Days of Repentance and the worthy ones fast, and the Holy One remits most of their sins. And when the Day of Atonement comes, all Israel fast, and the Holy One forgives all their sins. Rabbi Aha said: it is written, "For with You is forgiveness" (Psalms 130:4) -- forgiveness is stored up with You from the beginning. And why all this? "That You may be feared" (ibid.) -- so as to place the fear of You upon all Your creatures. From the Day of Atonement until the festival, all Israel are busy with commandments: this one busies himself with his sukkah and that one with his lulav. On the first festival day they take their lulavs and citrons in hand and praise the Holy One, and the Holy One says to them, "I have already pardoned you for what is past; from here on, reckon your sins." Therefore He said "on the first day." What is "on the first day"? The first for reckoning sins, from the first day of the festival.