“I wish you well”.
This one of the truly great line - delivered perfectly by TLJ.
Hitman at Verna’s: If I tell you, how do I know you won’t kill me?
Eddie Dane: Because if you told me and I killed you and you were lying, I wouldn’t get to kill you then. Where’s Leo?
~ Millers Crossing
Seems there’s an echo in here.
Not really, just clarifying, the exact quote is better than the paraphrase. 
“Jesus, I open my mouth, the whole world turns smart.”
“If you were important enough to lie to, you’d already be dead.”
Endeavour, season 5, episode 5, “Quartet”
I always thought the final line was the best one though:
“You know what yegg, I believe you.”
“I am gonna send you to a deep, dark place and I am gonna have fun doing it.”
ETA: Another good Eddie Dane line…
“Shut up! Or maybe you still got too many teeth.”
There are so many good ones here, I have trouble choosing:
This sounds threatening, unless you imagine saying it to your penis when that special someone is feeling frisky.
For Eddie Dane, it could be both!
“Mink is Eddie Dane’s boy”
Since it is Good Friday:
“He has a wife, you know…”
Oh, we’re going there, are we?
Apart from the sanitation, the medicine, education, wine, public order, irrigation, roads, a fresh water system, and public health, what have the Romans ever done for us?
“Stwike him, Centuwion. Stwike him wuffwy to the gwound!”
A good one from an episode of BoJack Horseman I watched the other night:
“When you look at everything through rose colored lenses, all the red flags just look like flags.”
Good one!
Damn! Should be “Knock him wuffwy to the gwound!”
I am getting old… 
I must not fear. Fear is the mind-killer. Fear is the little-death that brings total obliteration. I will face my fear. I will permit it to pass over me and through me. And when it has gone past, I will turn the inner eye to see its path. Where the fear has gone, there will be nothing. Only I will remain.
From Frank Herbert’s “Dune”
(If it can be considered a single line)