The Speech of Victory was a Klingon rite available when one warrior recognizes the other as a defeated enemy. As part of the rite, the vanquished must acknowledge the victor's success in the battle and treat them with respect. Afterwards, the victor could not deny the other warrior's right to a death with honor. Once spoken, it could not be retracted as it was considered a sacred bond.
After Worf defeated Malach at Deep Space 9, he invoked the Speech of Victory to explain why he had placed precedence on his oath to Starfleet over the Klingon Empire. (DS9 novel: Vengeance)