Amazing and moving Performance of "Unetanneh Tokef"

Recorded in the 13th century commentary Or Zarua, legend has it that Unetanneh Tokef was composed by a purported 11th-century sage named Rabbi Amnon of Mainz (or Mayence, in Germany) -- who, apart from this one story, is utterly unknown to history. Friends with the Archbishop of Mainz, Rabbi Amnon was pressured to convert to Catholicism. As a delaying tactic, he requested three days to consider the offer; immediately after, he regretted intensely giving even the pretense that he could possibly accept a foreign religion. After spending the three days in prayer, he refused to come to the bishop as promised, and, when he was brought to the bishop's palace, he begged that his tongue be cut out to atone for his sins. Instead, the bishop ordered his hands and legs amputated — limb by limb — as punishment for not obeying his word to return after three days and for refusing to convert. At each amputation, Rabbi Amnon was again given the opportunity to convert, which he refused.
This event occurred shortly before Rosh Hashanah. On that holiday, as he lay dying, Rabbi Amnon asked to be carried into the synagogue, where he recited the original composition of Unetanneh Tokef with his last breath. Three days later, he appeared in a dream to Rabbi Kalonymus Ben-Meshullam (died 1096), one of the great scholars of Mainz, and begged him to record the prayer and to see that it was included in the text of the High Holiday services. Thus, the legend concludes, Unetanneh Tokef became a part of the standard liturgy.
However, modern scholarship has demonstrated that the prayer is in fact considerably older than it was traditionally believed, with fragments found in the Cairo Geniza dating to the 8th Century.
While medieval history testifies amply to the intense persecution of Jews by Christians at the time of the Crusades, there are difficulties with the legend that it was composed by Rabbi Amnon of Mainz. Not least of these is its portrayal of R'Amnon as an illustrious Torah giant, while Jewish history of that period provides no record of a 'Rav Amnon of Mainz' at all. It seems unlikely that a person of such tremendous stature would be remembered only in a single legend.[4] Moreover, the discovery of the Unetaneh Tokef prayer within the earliest strata of the Cairo Geniza materials makes it almost impossible that the prayer could have been composed as the legend claims. Additionally, some scholars see parallels with non-Jewish hymnology, suggesting that elements of the prayer stemmed from other sources.[5]
Rather, the prayer was likely written by a payetan (perhaps Yannai) in the Land of Israel several hundred years earlier.[4] Authorship in the Land of Israel is corroborated also by internal evidence, such as the concluding three-part remedy of 'repentance, prayer, and charity', which is found in exact permutation in Genesis Rabbah (composed in the Land of Israel), yet not in Babylonian sources (e.g., Talmud Bavli cites a four-part remedy)
Unetaneh Tokef displays significant liturgical skill, seamlessly fusing concepts and language from ancient Biblical and Rabbinical source materials (see #Themes and Sources of Unetanneh Tokef).