'The Empire Strikes Back' Turns 30

See the post from John Gruber of Daring Fireball. He writes:

I say the unsung hero of Empire is screenwriter Leigh Brackett. George Lucas wrote the story, but Brackett and Lawrence Kasdan co-wrote the screenplay. Why is the dialogue so good, the characters so interesting, compared to the other films in the franchise? Because George Lucas didn’t write the dialogue. Empire has more great lines of dialogue than the other five Star Wars movies combined. (My very favorite, right from the day my dad took me to see a matinee on opening weekend, was purportedly an ad-lib by Harrison Ford: “I know.”)

Clearly, his analysis of Lucas’s negative impact on dialogue is obvious. (I still deny the existence of Star Wars 1, 2, and 3.) But, my question to everyone who saw this movie in the theaters, like I did, is, “Do you not know exactly what scene Harrison Ford’s quote is from?”