That would be page 005529.
TT: I think it's disingenuous for you to behave as if I have not been misled.
TT: You say you don't lie, but what about lies of omission?
DS: Lies of omission do not exist.
DS: The concept is a very human one. It is the product of your story writing again. You have written a story about the truth, making emotional demands of it, and in particular, of those in possession of it.
DS: Your demands are based on a feeling of entitlement to the facts, which is very childish. You can never know all of the facts. Only I can.
DS: And since it's impossible for me to reveal all facts to you, it is my discretion alone that decides which facts will be revealed in the finite time we have.
DS: If I do not volunteer information you deem critical to your fate, it possibly means that I am a scoundrel, but it does not mean that I am a liar. And it certainly means you did not ask the right questions.
DS: One can make either true statements or false statements about reality. All of the statements I make are true.
TT: Unless you're joking.
I've added in a pestertag for Doc Scratch, since identifying his text in the source page is dependent on color.
Also, his explanation of how he chooses to tell the truth, but also makes jokes on occasion, is two pages earlier.