Blood oath

In Klingon culture, a blood oath is a vow of vengeance that must never be broken.

In traditional Klingon history, a blood oath would be followed by rigorous celebration.

Klingon law is very serious about Blood oaths so much that even in law it is forbidden to break. Most of the time if a Blood oath was broken the individual or group who broke the pact was ostracized or even hunted and killed.

Kang, Kor, Koloth, and Curzon Dax swore a blood oath together to take revenge on the Albino for killing the Klingons' firstborn sons in 2290. Their blood oath was finally fulfilled in 2370, when they tracked down the Albino to Secarus IV, and successfully killed their enemy.

According to the oath, the four swore to cut out the heart of the Albino and eat it before his still-living eyes.