The Bre'Nan was a Klingon ritual performed during the preparation for a wedding. It was performed with the bride-to-be and the mistress of the Great House. If the mistress was not satisfied with the performance of the ritual, she had the option of canceling the wedding.
During Jadzia Dax's wedding preparations, the Bre'Nan was scheduled to be completed while Dax was having a party. The Lady Sirella demanded that the ritual be performed to her satisfaction, however Dax, who by now was noticeably intoxicated and fed up with Sirella's condescending attitude, wished to continue partying. After a heated argument briefly erupted into a physical altercation, Sirella, enraged by Dax's behavior, declared the wedding annulled with the words "Mok'Ta vor, kash a'VEH" ("You are an enemy of my house"). The Bre'Nan thus was not completed. (DS9: "You Are Cordially Invited").