Kol Nidre (Aramaic: כָּל נִדְרֵי) is an Aramaic declaration recited in the synagogue before the beginning of the evening service on every Yom Kippur, the Day of Atonement.
The song is a plea to be released from obligatins under Jewish law, obligations Jews in Spain could not meet under the threat of the Inquistion.
The formula proactively annuls any personal or religious oaths or prohibitions made upon oneself to God for the next year, so as to preemptively avoid the sin of breaking vows made to God which cannot be or are not upheld.