One of the books of the Bible considered apocryphal by Jerome-supporting Protestants though accepted by Orthodox Christians.
A document supposedly sent to the Judeans about to be taken captive in Babylonia. It's actually a religious tract condemning idolatry.
(The Origin of the Bible: Newly Updated by F. F. Bruce, J. I. Packer, Philip W. Comfort, and Carl F. H. Henry, 2020. Old Testament and New Testament Apocrypha by R. K. Harrison, Page 87.)
Fragments of it were found with the Dead Sea Scrolls.
(The Origin of the Bible: Newly Updated by F. F. Bruce, J. I. Packer, Philip W. Comfort, and Carl F. H. Henry, 2020. Texts and Manuscripts of the Old Testament by Mark R. Norton, Page 164)