The Klingon ceremony of ritual suicide for a warrior who can no longer stand and face his enemies, which Worf asks William Riker to help him perform after he is paralysed.
The Hegh'bat is the ritual by which a Klingon who is too badly injured to live as a warrior ends his life. A family member or trusted friend hands him the knife and, after he has stabbed himself in the heart, wipes the blade on his own sleeve. Tradition gives the duty to the eldest son.
It drives the episode Ethics in 2368. A falling container crushes Worf's spine and leaves him paralysed. Rather than live disabled, he asks William Riker to assist him. Riker is appalled, studies the ritual and tells Worf that by Klingon law the task falls to Alexander.
Unable to ask it of his young son, Worf instead accepts the untested genetronic procedure offered by Dr Toby Russell, which nearly kills him but restores his ability to walk.