HaAderet v'HaEmunah (Hebrew: האדרת והאמונה, 'The Glory and the Faith'), commonly referred to as LeChai Olamim (Hebrew: לחי עולמים), is a piyyut, or Jewish liturgical poem, sung or recited during Shacharit of Yom Kippur in virtually all Ashkenazic communities, and on Shabbat mornings in Chassidic communities.
[1] The source of this piyyut is originally found in Hekhalot Rabbati ("Greater Palaces"), a mystical text dating from the sixth century which describes the spiritual ascent of Rabbi Ishmael ben Elisha.
[2] HaAderet v'HaEmunah is written in the form of an alphabetical acrostic, as is common in the Hebrew Bible and subsequent pieces of Jewish liturgy.
[citation needed] In Chabad there are several tunes to the words of this piyyut: The Hasidic courts of Boyan and Toldos Aharon also have unique melodies for HaAderet v'HaEmunah.
A line from this piyyut was adapted as the title of a journal published by Yosef Yitzchak Schneersohn in 1940, Hakeri'ah vehakedusha ("The Declaration and the Holiness").