A religious poem that is meant to strike fear in us.
Though this article mentions Rosh Hashanah specifically, it should be noted that the Unetanah Tokef is also part of the Yom Kippur liturgy. This article is excerpted from Entering the High Holy Days. Reprinted with permission from the Jewish Publication Society.
On both days [of Rosh Hashanah], the magnificent Unetanah tokef (we shall ascribe holiness to this day) is chanted prior to the Kedushah. Although there are popular legends concerning the origin of this piyyut, we do not know who wrote it. What is certain is that the poet was extremely gifted. The structure of the poem and its language suggest that it was composed during the Byzantine period.
The concepts on which it is based come from Jewish apocalyptic literature and parallel Christian writings based on similar sources, the most famous of which is the Dies irae (day of wrath)-‑found in the requiem mass-‑which offers a vivid description of the day of judgment for all humankind. In Unetanah tokef, however, the subject is not the final judgment but the much more immediate, yearly day of judgment--Rosh Hashanah. The text of this piyyut follows.
We shall ascribe holiness to this day.
For it is awesome and terrible.
Your kingship is exalted upon it.
Your throne is established in mercy.
You are enthroned upon it in truth.
In truth You are the judge,
The exhorter, the all‑knowing, the witness,
He who inscribes and seals,
Remembering all that is forgotten.
You open the book of remembrance
Which proclaims itself,
And the seal of each person is there.
The great shofar is sounded,
A still small voice is heard.
The angels are dismayed,
They are seized by fear and trembling
As they proclaim: Behold the Day of Judgment!
For all the hosts of heaven are brought for judgment.
They shall not be guiltless in Your eyes
And all creatures shall parade before You as a troop.
As a shepherd herds his flock,
Causing his sheep to pass beneath his staff,
So do You cause to pass, count, and record,
Visiting the souls of all living,
Decreeing the length of their days,
Inscribing their judgment.
On Rosh Hashanah it is inscribed,
And on Yom Kippur it is sealed.
How many shall pass away and how many shall be born,
Who shall live and who shall die,
Who shall reach the end of his days and who shall not,
Who shall perish by water and who by fire,
Who by sword and who by wild beast,