How is “have your doubts” used?

In The Dawn Wall (2017), one line is: “I really had my doubts as to whether it was going to be a viable climb.”

Which movie is “have your doubts” from?

The clip at the top of this page is from The Dawn Wall (2017).

to have reasons why you are not certain about whether sth is good or whether sth good will happen

Heard in 5 moviesPlay Idioms

Oxford100% of films
to have reasons why you are not certain about whether sth is good or whether sth good will happen
I really had my doubts as to whether it was going to be a viable climb.
I mean, trust me, I had my doubts after your whole jam debacle.

Definitions from the Oxford Advanced Learner's Dictionary, 9th edition

I really had my doubts as to whether it was going to be a viable climb.

Said in 3 films · #1