Stevie Wonder is joining some of the NFL’s biggest stars in defiance of President Donald Trump’s attack on players who refuse to stand during the U.S. national anthem in protest of police violence against African-Americans.

The growing fracas began when President Donald Trump spoke at a rally for Alabama Senate candidate Luther Strange on Friday. During his meandering 90-minute speech, the president waded into the wide world or sports by bringing up NFL players who choose to take a knee rather than stand for the anthem.

Trump asked the crowd: “Wouldn’t you love to see one of these NFL owners when somebody disrespects our flag to say, ‘Get that son of a b**ch off the field right now’?”

Added Trump: “He’s fired! He’s fired!”

Trump also bashed those players for their “total disrespect of our heritage” and “everything that we stand for.”

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Trump’s words were roundly criticized by NFL players, and even NFL Commissioner Roger Goodell issued a terse response chiding Trump for his “divisive comments” and “unfortunate lack of respect for the NFL.”

“The NFL and our players are at our best when we help create a sense of unity in our country and our culture,” reads Goodell’s statement. “There is no better example than the amazing response from our clubs and players to the terrible natural disasters we’ve experienced over the last month.  Divisive comments like these demonstrate an unfortunate lack of respect for the NFL, our great game and all of our players, and a failure to understand the overwhelming force for good our clubs and players represent in our communities.

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On Saturday, Trump not only rescinded his White House invitation to Golden State Warriors star Steph Curry, he doubled down on his attacks, posting a couple of tweets blasting NFL players who “disrespect our Great American Flag (or Country),” adding once more: “YOU’RE FIRED.”

Trump’s earlier remarks and subsequent Twitter tirade were met with fierce resistance on social media, including a scathing response from Diddy, who offered a video message to “all the players in the NFL” via Instagram.

“I just wanna send some blessings and also, you know, some support to all the players in the NFL,” says Diddy in the video.

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“My message to y’all — even though you ain’t asking, so please receive it because I rarely give ‘em in this way — y’all got a chance to do something really, really, really, really, really great tomorrow,” he adds. “If you all do whatever you do in unity, you can’t be stopped. Just do the math, man. Do the math, stick together, stand up for each other, ride with each other because believe me, we’re all we got and it has nothing to do with football or business. Y’all are our stars, y’all represent us, y’all are our strong heroes. So show that strength, please.”

Other celebs followed Diddy’s lead, including “Insecure” star Issa Rae (who retweeted Diddy’s video), political commentator Keith Olbermann (who urges all players and fans to stop standing during the anthem) and even musician John Mayer.

In addition, a who’s who of NFL players took to Twitter to voice their opposition of Trump’s inflammatory statements.

Trump, however, appears to be unmoved by the backlash, even issuing a tweet slamming Goodell’s statement. “Tell them to stand!” tweeted the president.

On Saturday night, music legend Stevie Wonder added his voice to the movement by taking a knee during his performance at the Global Citizens Festival in New York City.

“Tonight, I’m taking a knee for America; but not just one knee, I’m taking both knees,” said Wonder prior to his performance as his son, Kwame Wonder, helped him to kneel. “Both knees in prayer for our planet, our future, our leaders of the world and our globe. Amen ...” Watch:

Meanwhile, Trump returned to Twitter to continue bashing the NFL, mocking the league’s ratings troubles and suggesting fans boycott games until the NFL gets its protesting players in line.