Kol Nidre prayer of Yom Kippur, from a 19th century machzor.

Kol Nidre: For many Jews, the essence of the Yom Kippur service takes place at the very beginning of the holiday, at the evening service that ushers in Yom Kippur.  The name is derived from the first major piece of the Yom Kippur prayers, dramatically chanted at the evening service.  All Torahs are taken out, the entire congregation stands, and the cantor chants this formula three times.  While most people think that Kol Nidre is a prayer, it is actually a legal formula.  It begins with an expression of repentance for all unfulfilled vows, oaths, and promises to G-d during the previous year.  It was in use as early as the 8th century, perhaps as a means of annulling oaths forced on Jews by their Christian persecutors.

The first time it is chanted, he must utter it very softly, like one who hesitates to enter the palace of the king to ask a gift of him whom he fears to approach; the second time he may speak somewhat louder; and the third time more loudly still, as one who is accustomed to dwell at court and to approach his sovereign as a friend.