Then, after the marriage, I found out from the doctor that the old man might live to be eighty.

5 seconds sound clip from the Dead Reckoning (1947) movie soundboard.

You can hear this line at 01:32:55.412 in the Blu-ray version of the movie.

Quote context

[...]

- Man, are you crazy?

- Either I get that Chandler gun, or the slow broiler for you, even if we all cook.

- You're insane. Can't you see I'm telling the truth?

- Old Chandler was so anxious, he not only offered her marriage, he told her he had a bad heart, and, in six months, she'd come into all his money.

- On the level, friend!

- Then, after the marriage, I found out from the doctor that the old man might live to be eighty.

- That night, Johnny Preston had a quarrel with Chandler, and people heard it. That was all I needed.

- I followed the old man home and shot him, with Coral's gun.

- The Preston kid thought she did it, took the rap.

- Listen to me. If you don't believe this, how do you suppose I knew Johnny had come back to Gulf City? From her, obviously!

[...]