Ivanhoe, page 34

"Yield thee, De Bracy," said the Black Champion, stooping over him, and holding against the bars of his helmet the fatal poniard with which the knights despatched their enemies, and which was called the dagger of mercy - "yield thee, Maurice de Bracy, rescue or no rescue, or thou art but a dead man."
"I will not yield," replied De Bracy faintly, "to an unknown conqueror. Tell me thy name, or work thy pleasure on me; it shall never be said that Maurice de Bracy was prisoner to a nameless churl." The Black Knight whispered something into the ear of the vanquished. "I yield me to be true prisoner, rescue or no rescue," answered the Norman, exchanging his tone of stern and determined obstinacy for one of deep though sullen submission.