Billionaire investor Warren Buffett ripped into Republican Donald Trump Monday over his refusal to release tax returns, his business bankruptcies, and his attack on a fallen soldier’s family, repeating a famous phrase from the McCarthy era, “have you no sense of decency, sir?”

Buffett, campaigning on behalf of Democratic presidential nominee Hillary Clinton, challenged Trump to meet him “any place, any time” with a copy of his tax returns. Buffett said he would bring his returns and the two of them would answer questions from the public. He dismissed Trump’s contention that he couldn’t release them because he’s being audited. Buffett said his return is being examined by the Internal Revenue Service as well.

“You’re only afraid if you’ve got something to be afraid about,” Buffett told a cheering crowd in Omaha. “He’s not afraid because of the IRS, he’s afraid because of you.”

Trump’s refusal to release tax returns -- which 2012 GOP nominee Mitt Romney has called “disqualifying” -- would break with 40 years of precedent if he holds his position through the November election, and the issue resonates with voters. In a Bloomberg Politics national poll conducted in June, two-thirds said Trump’s withholding bothered them at least a little.

The 85-year-old Buffett, known as the Oracle of Omaha, criticized Trump’s record as a businessman and said the “final straw” was the Republican presidential nominee’s swipe at the heartbroken parents of a Muslim-American war hero killed in Iraq, which has sparked condemnation across party lines.

Question of Sacrifice

Responding to a speech at the Democratic convention last week by Khizr Khan, who spoke about the death of his son, Army Captain Humayun Khan, while serving in Iraq in 2004, Trump said he had “sacrificed” for the U.S. by employing “thousands and thousands of people.”

Buffett said he and Trump have done very well and “we haven’t sacrificed anything.”

Clinton is campaigning in solidly Republican Nebraska with Buffett’s help to burnish her credentials with the business community and to try to make the most of the state’s unusual method of apportioning its five Electoral College votes.

The Berkshire Hathaway Inc. chairman and chief executive officer introduced Clinton at a Monday evening rally in Omaha that’s focused on the Democratic nominee’s economic plans. Clinton is seeking to showcase her support from prominent business leaders as she makes a play for the votes of independents and Republicans who are uncomfortable with the prospect of Trump in the White House. Buffett’s fellow billionaire, entrepreneur Mark Cuban, endorsed Clinton at a rally Saturday in Pittsburgh.