I gave you a rough transcript of this exchange earlier, but given it's the one getting the most attention from Mr Trump's critics, I thought I'd go back and do a more thorough job.
At issue is whether the President failed to condemn white supremacists.
Wallace: "Are you willing tonight to condemn white supremacists and militia groups-"
Trump: "Sure."
Wallace: "-and to say that they need to stand down and not add to the violence in a number of these cities, as we saw in Kenosha and as we've seen in Portland?"
Trump: "Sure, I'm willing to do that."
Biden: "Then do it."
Wallace: "Then go ahead, sir."
Trump: "But I would say almost everything I see is from the left wing, not from the right wing."
Wallace: "So what are you, what are you saying?"
Trump: "I'm willing to do anything. I want to see peace."
Wallace: "Then do it, sir."
Biden: "Say it. Do it. Say it."
Trump: "Do you want to call them – what do you want to call them? Give me a name. Give me a name. Go ahead, who would you like me to condemn? Who?"
Wallace: "White supremacists and right wing militias."
Biden: "The Proud Boys. The Proud Boys."
Trump: "The Proud Boys. Stand back and stand by. But I'll tell you what, I'll tell you what, somebody has got to do something about Antifa and the left. Because this is not a right wing problem, this is a left wing problem."
Biden: "His own FBI director said the threat of white supremacists-"
Trump: "This is a left wing problem."
Biden: "Antifa is an idea, not an organisation."
Trump: "Oh you've got to be kidding me. OK."
Biden: "That's what his FBI, his FBI director said."
Trump: "You know what? He's wrong. Antifa is not an idea. Antifa is bad."
For context here, the Proud Boys have been identified as a hate group by the Southern Poverty Law Centre, which tracks extremist organisations.
And this quote from FBI Director Christopher Wray is the one Joe Biden was referring to.
“It’s not a group or an organization. It’s a movement or an ideology," Mr Wray told a congressional hearing earlier this month.
Mr Wray did also stress that Antifa is a "real thing" and a serious concern.