Warren Buffett challenged Donald Trump Monday to discuss their tax returns publicly.

"I'll bring my tax return. He can bring his tax return...Just let people ask us questions about items on there," Buffett said in his introduction of Hillary Clinton at an Omaha rally. "Nobody is going to arrest us. There are no rules against showing your tax returns."

The Omaha billionaire said he's willing to meet Trump any where and any time before Election Day to let the public inquire about their tax filings. Tax returns reveal a lot more about a person's finances than financial statements do, Buffett said.

Trump has resisted releasing his returns, saying he is being audited by the IRS. This breaks with the longstanding tradition that presidential candidates release at least some recent tax returns. It's also unclear whether Mike Pence, Trump's running mate who is Indiana's governor, will make his returns public.

Related: Nixon released his tax returns under audit. Why can't Trump?

Many experts, however, say that being audited doesn't stop Trump from revealing his returns.

Buffett acknowledged that he, too, is under audit, but said that's not a reason to withhold tax returns.

Related: Will the public get to see Mike Pence's tax returns?

The only reason to keep your tax return private is if you have something to hide, Buffett said.

"You're only afraid if you've got something to be afraid about," he said. "He's not afraid because of the IRS. He's afraid because of you."