Which liturgical poem beginning 'Let us now relate' is recited on Rosh Hashanah?

Which liturgical poem beginning “Let us now relate” is recited on Rosh Hashanah? The poem is Unetanneh Tokef, also spelled Unetaneh Tokef.

Its opening phrase introduces a meditation on the awe and holiness of the Day of Judgment. The poem describes God reviewing the deeds of humanity and presents the coming year as a time when lives and destinies are considered. It concludes with the famous triad of repentance, prayer and charity, which are understood to mitigate the severity of the decree.

In many Ashkenazi communities, Unetanneh Tokef is recited during the repetition of the Mussaf Amidah, with the congregation often standing and the Torah ark open. It is also associated with Yom Kippur, so it is not exclusively a Rosh Hashanah prayer. Sephardic practice varies, and some communities omit it or place it differently.

A popular medieval legend attributes the poem to Rabbi Amnon of Mainz, but historians debate its authorship and date. Leonard Cohen’s 1974 song “Who by Fire” was inspired by its imagery.