MSNBC host Al Sharpton revealed a secret of his own on Friday regarding Bill O'Reilly: that his Fox News counterpart, who has publicly denigrated him, has worked with Sharpton's activist organization.

"This is the worst kind of gutter talk," Sharpton said after playing clips of O'Reilly calling him a "race-hustler." "But if Bill really thinks that about me, why did he agree to speak at a conference for my civil rights group, the National Action Network, a few years ago? Look -- there he is, at a convention for the 'grievance industry.'"

Sharpton also slammed O'Reilly for revealing that he once donated $25,000 to Sharpton for charitable purposes to a community he has called "parasites." O'Reilly claimed he broke his silence regarding the gesture in order to expose Sharpton's character.

"The sad truth is, the good that Bill did with the check he wrote is far outweighed by the vile and hateful things he says on the air night after night," Sharpton said. "Bill is playing to the extremists in his audience, and it shows. It shows what's wrong with the right wing today."

Watch Sharpton rebuke O'Reilly, as aired on MSNBC Friday, below.

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