Traveling through time has become much too painful.
3 seconds sound clip from the Back to the Future Part III movie soundboard.
You can hear this line at 01:11:38.595 in the DVD version of the movie.
Quote context
[...]
- Doc, listen. Maybe we I don't know, maybe we can just take Clara with us.
- As you reminded me, Marty, I'm a scientist, so I must be scientific about this.
- We shall proceed as planned, and as soon as we return to 1985, we'll destroy this infernal machine.
- Traveling through time has become much too painful.
- Goodbye? Well, where are you going?
- I'm going away. And well, I'm afraid I'll never see you again.
- Emmett!
[...]