What I am about to tell you has never been told to another living soul.
5 seconds sound clip from the Garfield's Halloween Adventure (1985) movie soundboard.
You can hear this line at 00:16:59.370 in the Blu-ray version of the movie.
Quote context
[...]
- Let's warm ourselves by the fire. Ah... This is more like it.
- Shut up, you two. That's enough to stop an old man's ticker.
- I knew it. Let's not bother the man any longer, Odie.
- Stay!
- What I am about to tell you has never been told to another living soul.
- This island has a secret. A deep, dark secret it has held for 100 years.
- One hundred years ago, tonight, a ruthless band of pirates held up in this very house.
- They had looted many ships and were pursued by government troops.
[...]