Stevie Wonder took a not-so-subtle jab at President Trump by taking a knee on stage before performing at a festival Saturday in New York’s Central Park.

“Tonight, I’m taking a knee for America,” the singer said as he held on to his son, Kwame Morris, who knelt next to his father. “But not just one knee; I’m taking both knees. Both knees in prayer for our planet, our future, our leaders of the world and our globe. Amen.”

Wonder did not mention the president by name, but his decision to take a knee on stage came the day after Trump used profane language to attack the national anthem protests being staged by National Football League players.

“Wouldn’t you love to see these NFL owners, when somebody disrespects our flag, to say: ‘Get that son of a b—- off the field right now, out. He’s fired. He’s fired!’ ” Trump told a crowd Friday in Huntsville, Ala. “You know, some owner is going to do that. He’s going to say, ‘That guy that disrespects our flag, he’s fired.’ And that owner, they don’t know it, [but] they’ll be the most popular person in this country.”

Trump did not name anyone, but the national anthem protest was popularized by San Francisco 49ers quarterback Colin Kaepernick, who knelt last season to draw attention to police violence against African Americans. The president doubled down on his attacks Saturday, angering National Basketball Association superstars Stephen Curry and LeBron James, and drawing criticism from NFL Commissioner Roger Goodell.

Tensions continued to grow Sunday, when Trump called on NFL owners to fire or suspend players who protest, encouraged NFL fans to boycott games and claimed that attendance and ratings are “WAY DOWN.” In a show of defiance against Trump, dozens of players from the Baltimore Ravens and Jacksonville Jaguars stood with their arms locked in solidarity or took a knee before the game’s kickoff Sunday morning in London’s Wembley Stadium.

Before he took a knee on stage, Wonder also spoke against the insults Trump traded with North Korean leader Kim Jong Un, again without naming the president.

“We must take care of each other and this planet. If we don’t … we would lose the ultimate video game of life. … Weapons are real and rhetoric is dangerous,” he said, mentioning the United States and North Korea. “What we do know is how we work towards a planet that can save and serve our lives and protect our future.”

Wonder performed a medley of his classic hits at the Global Citizen Festival on the Great Lawn in Central Park, including “Higher Ground,” “Signed, Sealed, Delivered I’m Yours” and “Overjoyed.” Before he sang, he urged the audience to reject hate, bigotry and sexism.

Social media erupted Saturday evening after Wonder took a knee on stage. Many lauded the singer for what they viewed as his expression of solidarity with Kaepernick.

Others, however, called Wonder ungrateful.

Wonder has been politically vocal, openly supporting former president Barack Obama and 2016 Democratic presidential candidate Hillary Clinton.

During Clinton’s 69th birthday in October, Wonder surprised her with a rendition of “Happy Birthday” and wore a jacket emblazoned with the words “1st Woman President.”

“Truth be told, I think we as men have had our chance to work it out. It’s time to let a woman do it,” he said, according to Rolling Stone.

During a telethon fundraiser for victims of Hurricanes Harvey and Irma, Wonder began the broadcast with an invocation promoting equality and criticizing climate change deniers.

“And anyone who believes that there’s no such thing as global warming must be blind or unintelligent,” he said, according to the Atlantic. “Lord, save us all.”

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