Sacred texts existed related to Klingon spirituality.
Stories of the Klingon Empire founder Kahless the Unforgettable were within the pages of the texts, with one exception. However, the story of the forging of the Sword of Kahless was never written down, being known only by the Guardians so that they might use it for proving the veracity of an individual's claim of being Kahless.
According to the texts, Kahless would return to the Klingons in the Caves of Boreth. In the late 2360s, the Guardians gave the experiences of Kahless as recorded in the sacred texts to their clone of Kahless. There experiences were considered as a exceptional form of memory. (TNG: "Rightful Heir")
During the 23rd century, a group of Klingons discovered sacred texts in scroll form telling them to embark on a journey to a distant part of the galaxy and seek out the kuvah'magh. One of the followers of this texts, Kohlar, admitted that they might be divinely inspired or scrawled by a madman in a cave. (VOY: "Prophecy")