The Story of the Promise
The Story of the Promise was a Klingon legend from the time of Kahless the Unforgettable. This legend was preseved in the sacred texts. 

According to the story, after Kahless had united the people and gave them the laws of honor, he saw his work completed. One night, he gathered his belongings and departed to a city's limits. The people wept and begged him not to leave; however, Kahless was undeterred. Speaking to the people, he said, "You are Klingons. You need no one but yourselves. I will go now to Sto-vo-kor. But I promise one day I will return." He pointed to a star in the sky, and instructed the people to look for him "on that point of light."

The  of the Followers of Kahless later established a monastery on the planet Boreth, which orbited the star that Kahless had pointed to, in order to await his return. ()
Story of the Promise
Story of the Promise