Jake Gyllenhaal reveals the reason why Heath Ledger refused to present at the 2006 Oscars

He was irked by a planned "Brokeback Mountain" joke.

Speaking to Another Man magazine for the Summer/Autumn 2020 issue, Gyllenhaal opened up about his profound respect for Ledger and his unshakeable morals.

The 39-year-old explained that the 2006 Oscars had written in a joke about "Brokeback Mountain" in the opening monologue, which irked Ledger.

"I mean, I remember they wanted to do an opening for the Academy Awards that year that was sort of joking about it," the "Spider-Man: Far From Home" star explained. "And Heath refused. I was sort of at the time, 'Oh, okay... whatever.' I’m always like: it’s all in good fun. And Heath said, 'It’s not a joke to me -- I don’t want to make any jokes about it.'"

Gyllenhaal touched upon how Ledger's stance was probably considered revolutionary back then, adding that his late co-star's decision to refuse the Oscars was "absolutely" smart.

Touching more on "Brokeback Mountain" in the interview, the actor also commented on why he became involved in the Ang Lee movie even though he, as a heterosexual man, didn't fully understand the romantic relationship in the film.

"There are things you’re chosen for -- a quality, an essence -- and Ang did that," said Gyllenhaal. "And it’s still a mystery to me. And something that Heath and I shared; that it was a mystery to us at the time."

Ledger died of an accidental drug overdose on Jan. 22, 2008. He was 28.