The only thing the command module's good for is re-entry. So, that leaves us with the LEM, which means free-return trajectory.
8 seconds sound clip from the Apollo 13 movie soundboard.
You can hear this line at 01:08:44 in the Blu-ray version of the movie.
Quote context
[...]
- I'm not gonna sugarcoat this for you!
- Okay, hold it. Let's hold it down. Let's hold it down, people.
- The only engine we've got with enough power for a direct abort is the SPS on the service module.
- It could have been damaged in an explosion, so, let's consider that engine dead.
- I'm wondering what the Grumman guys think about this.
- We can't make any guarantees.
- We designed the LEM to land on the moon, not fire the engine up there for course corrections.
- Well, unfortunately, we're not landing on the moon, are we?
[...]