The Return of Sherlock Holmes
"I owe you many apologies, my dear Watson, but it was all-important that it should be thought I was dead, and it is quite certain that you would not have written so convincing an account of my unhappy end had you yourself not thought it was true." (Empty House.34)
"I have done no harm."
"No harm? You have done your best to get an innocent man hanged. [....]
The wretched creature began to whimper.
"I am sure, sir, it was only my practical joke." (Norwood Builder.185-189)
"Don't you think, Mr Cubitt," said he, at last, "that your best plan would be to make a direct appeal to your wife, and to ask her to share her secret with you?"
Hilton Cubitt shook his head.
"A promise is a promise, Mr. Holmes. If Elsie wished to tell me she would. If not, it is not for me to force her confidence. [....]" (Dancing Men.33-34)