'Look at us both': Biden laughs then fires back at Trump for questioning his mental health

In an interview with ABC's David Muir, Democratic presidential nominee Joe Biden laughed and then fired back at Donald Trump when asked about the president's comments about his mental health.

With Muir asking about the president talking about Biden's "mental fitness," the former vice president was quick to respond.

"Watch me, Mr. President, watch me," Biden responded. "Look at both, what we say, what we do,  what we control. What kind of shape we're in, c'mon."

"Look, I think it's a legitimate question to ask anybody over 70 years old," he continued. "Whether or not they're fit, whether they're ready. I say to the American people, watch me."

Watch below: