Author of the piyut, “Unesana Tokef”
Rav Amnon Magentza of Mainz was one of the gedolei hador in the 11th century. He was learned in Kabbalah, and was wise in all forms of wisdom. He was a wealthy and handsome man from a family of distinguished yichus.
In his beis medrash there was a miraculous ner tamid that burned all week long without oil! (Seder HaDoros)
Rav Amnon enjoyed a close relationship to the king. The royal ministers tried daily to get him to renounce his faith and become an apostate. He never paid them any heed until one day the king himself asked him to give up his faith. Feeling uncomfortable in front of the king, he sought a way to extricate himself from this confrontation and simply said, “Give me three days’ time to think about it.”
He was never really going to consider the request at all; he only made the statement as an excuse to gain time. Still, the matter gave Rav Amnon no rest. He was tormented by the fact that he had given the king even the merest impression that he would ever give up his faith. How could he have made it even seem that he was willing to even consider renouncing his emunah in Hashem and the Torah?! His friends and family tried to console him to no avail. After three days passed, he refused to appear before the king. When the king called him to stand judgment before him for failing to arrive, he said that he would pass judgment on himself and announce a fitting punishment for his misdeed:
“My lying tongue that spoke falsely should be cut out,” he proclaimed. Rav Amnon felt that it would be a kiddush Hashem since he had spoken as if he considered the possibility of leaving his faith.
“No,” the king declared, “I will cut off the feet that failed to bring you to come before me and we will torture your body.” As they cut off each of his limbs, they asked him to reconsider and to renounce his faith and accept theirs. Though he suffered horribly, he staunchly refused. Finally, with the stages of torture concluded, the king had him placed in a wood box alongside all his dismembered limbs. In this manner, they had him brought home.
Seder HaDoros says that this is why he was named Amnon because he truly believed with full faith in the living G-d – E”l Chai . [Translator’s note: Perhaps Amnon is a pseudonym, or alternatively, it was his given name and the statement is a derash that his true name proved his faith in Hashem.]
On Rosh Hashanah, Rav Amnon requested that they carry him to shul in the box, along with his dismembered limbs. They placed him by the chazzan. He accepted his terrible pain and suffering lovingly as penance for his crime. When the chazzan reached Kedushah, Rav Amnon asked him to pause. “Let me sanctify Hashem’s name in public,” he announced and proceeded to recite the famous liturgical poem, Unesana Tokef. At that moment, his soul departed.
Three days later he appeared to Rabbeinu Kalonymous ben Rabbeinu Meshulam and taught him the words to the poem and asked that it be taught and spread among Klal Yisroel. It was thus established that it be recited annually each Rosh Hashanah. In this way, Klal Yisroel would be remembered favorably before Hashem in connection to the great rectification that Rav Amnon made. (This is based on hand written accounts from old machzorim that belonged to Rav Yitzchok of Vienna, author of the Ohr Zarua who testifies that he found this story in the writings of Rav Ephraim ben Yaakov of Vienna and the Seder HaDoros says he saw it in an ancient German machzor.)