Roger Stone will have some serious explaining to do next time he sees Donald Trump. Stone, Trump’s most trusted adviser for decades, was reportedly caught talking trash about the former president, going so far as to call him the “greatest single mistake in American history.” The Washington Post has obtained extraordinary documentary footage of Stone as he worked to overturn the 2020 election. In one section, filmed on Joe Biden’s Inauguration Day, the Post reports that Stone can be seen in a car with the filmmakers when he lets rip on Trump. After describing his ally as America’s worst ever mistake, Stone said Trump would regret failing to pardon himself, saying: “A good, long sentence in prison will give [Trump] a chance to think about it, because the Southern District is coming for him, and he did nothing.” After his rant, Stone is reported to have turned to the filmmakers and said: “Obviously if you use any of that, I’ll murder you.” In an interview with The Daily Beast on Friday morning, Stone pushed back on the Post recounting of the documentary and said it contained several errors.