While introducing Hillary Clinton at a presidential campaign rally in Omaha, Nebraska, on Monday, billionaire Warren Buffett challenged Donald Trump over his war of words with the family of a fallen Muslim U.S. soldier. "I ask Donald Trump: 'Have you no sense of decency, sir?'" Buffett said, comparing the incident with the anti-communist McCarthy hearings in the 1950s. Buffett also dismissed Trump's claim that building his business empire constituted a sacrifice, while noting that his own family had not suffered as has the family of Army Capt. Humayun Khan, who was killed in Iraq. "Me, my family . . . Trump and his family have sacrificed nothing; building buildings is not sacrifice," Buffett said. The founder of Berkshire Hathaway also called for the Republican nominee to release his tax return. Buffett said he, like Trump, is under an IRS audit, and volunteered to meet with Trump and go over each other's tax returns together. Buffett also urged voters to turn out in November, and said he would help drive people to the polls who otherwise would not get out to vote.