Great Expectations by Charles Dickens Chapter 18 Page 17

“I should think not! Now you are to understand, secondly, Mr. Pip, that the name of the person who is your liberal benefactor remains a profound secret, until the person chooses to reveal it. I am empowered to mention that it is the intention of the person to reveal it at first hand by word of mouth to yourself. When or where that intention may be carried out, I cannot say; no one can say. It may be years hence. Now, you are distinctly to understand that you are most positively prohibited from making any inquiry on this head, or any allusion or reference, however distant, to any individual whomsoever as the individual, in all the communications you may have with me.

If you have a suspicion in your own breast, keep that suspicion in your own breast. It is not the least to the purpose what the reasons of this