Historian Rutger Bregman, in collaboration with NowThis, has released a tape featuring a heated conversation he says he had with Fox News host Tucker Carlson.

“You are a millionaire funded by billionaires, that’s what you are... You’re part of the problem,” Bregman can be heard saying just before Carlson goes into an expletive-filled tailspin.

“Moron... I wanna say to you why don’t you go fuck yourself ― you tiny brain,” the host replies. “And I hope this gets picked up because you’re a moron. I tried to give you a hearing, but you were too fucking annoying.”

The pre-recorded interview was supposed to air on Carlson’s show, according to Bregman and Carlson. The Dutch historian and author had been invited to talk to the Fox News host after he made incendiary remarks at the World Economic Forum in Davos, Switzerland, and accused rich people of not paying their fair share of taxes, according to The Guardian.

Carlson addressed the video on Wednesday night, saying he was incensed by Bregman’s remark that Fox News tells him what he can say.

“Whatever my faults or those of this channel, nobody in management has ever told us what positions to take on the air, never. Not one time,” said Carlson, before saying he and others on Fox News have “total freedom.”

The host added that he did what he tries hard never to do and was “rude.” Carlson said that while he felt what he said was accurate, the vulgar terms were not allowed to be used on television, so the segment could not be aired.

“There is some profanity, and I apologize for that. On the other hand, it was genuinely heartfelt and I meant it with total sincerity,” Carlson said.

Bregman’s tweets last week suggest the interview happened earlier this month and was supposed to air on Feb. 11.

The historian tweeted that Carlson later sent him an email saying: “I loved what you said at Davos, so I had high hopes for our interview. But you turned out to be far dumber, more dogmatic and less impressive than I expected. You’re [a] professional academic, so I guess I shouldn’t be surprised, but it was still disappointing. Also, for what it’s worth, you’re an asshole.”