Frank Oz: Yoda
Yoda : Remember, a Jedi's strength flows from the Force. But beware. Anger, fear, aggression. The dark side are they. Once you start down the dark path, forever will it dominate your destiny. Luke... Luke... do not... do not underestimate the powers of the Emperor or suffer your father's fate you will. Luke, when gone am I... the last of the Jedi will you be. Luke, the Force runs strong in your family. Pass on what you have learned, Luke. There is... another... Sky... walker.
Luke : Master Yoda... is Darth Vader my father?
Yoda : [avoiding the subject] Rest I need. Yes. Rest.
Luke : Yoda, I must know. If you know, tell me.
Yoda : Your father he is.
Yoda : Told you, did he?
Luke : Yes.
Yoda : Unexpected this is. And unfortunate.
Luke : Unfortunate that I know the truth?
Yoda : No! Unfortunate that you rushed to face him... that incomplete was your training. That... not ready for the burden were you.
Yoda : [Deleted Scene - A dying Yoda confesses to Luke about the truth about Darth Vader] Unfortunate that you must rush to face him. And in complete of your training. That no ready the burden with you. Obi-Wan would had told you long ago if I had let him. Now, a great weakness you carry. Fear for you, I do. Face Vader you must and "sorry" will not help.