Many National Football League players across the country protested Sunday by kneeling, linking arms or staying the locker room during the National Anthem.

It was in response to a comment made by President Donald Trump during a political rally Friday in Huntsville to campaign for U.S. Senator Luther Strange.

“Wouldn’t you love to see one of these NFL owners when somebody disrespects our flag to say get that son of a [expletive] off the field right now, out, he’s fired,” Trump told the Huntsville crowd.

Since that comment, a picture of Dr. Martin Luther King Jr. kneeling in Selma with a group of protesters in 1965 has been shared by many on social media in response to Trump.

The King Center, which was founded by Coretta Scott King, tweeted the photo Saturday with the hashtag #takeaknee.

“People didn’t approve of the way my father protested injustice either; said he was causing trouble, called him an ‘outside agitator.’ #MLK,” King’s daughter Bernice King tweeted Sunday.

Cincinnati Bengals defensive end and Dallas County native Michael Johnson stood for the National Anthem and locked arms with his teammates before their game against the Green Bay Packers Sunday.

Johnson told the Cincinnati Enquirer the action represented “One family. Solidarity.”

John Legend, who performed the song “Glory” from “Selma” the movie on the Edmund Pettus Bridge in January 2015, mentioned the city and the impact of the protests in 1965 in an essay he wrote for Slate magazine.

“Protests in Selma, Alabama, changed the trajectory of this nation and catapulted the Voting Rights Act into being,” Legend wrote. “Soon after images of Bloody Sunday flooded television sets, President [Lyndon B.] Johnson presented to Congress the Voting Rights Act, which would remove barriers to voting like literacy tests.”

Legend called protests patriotic in the piece.

“Protest has played a critically important role in elevating the voices of the most vulnerable in our nation. Protest in America has been essential to ending war, to demanding equal rights, to ending unfair practices that keep citizens marginalized,” Legend wrote. “If we quell protest in the name of patriotism, we are not patriots. We are tyrants.”

Civil rights icon John Lewis, who marched alongside King in Selma during the voting rights movement, also responded in a tweet.

“During another period, we knelt. There is nothing wrong with kneeling down to stand up against injustice. It’s protected by the Constitution,” Lewis tweeted. In another tweet, he said, “The young people kneeling today are following a long tradition.” The tweet was accompanied by a photo of himself kneeling as a young man.

Several comments on social media indicated Ellwood Christian School football players knelt in protest Friday night before their game against Maplesville, but that is not the case, according to head coach Mike Stokes. Players were kneeling, but it wasn’t in protest, Stokes said.

“That wasn’t even planned for us to do that actually. We were warming up down in the end zone, and they said let us pray, so my kids took their helmets off and got down on one knee and prayed,” Stokes said. “By the time they got through praying they went straight into the National Anthem, so the kids didn’t stand because they really didn’t have time.”

Stokes said most of his players stayed kneeling, turned to the flag and put their hands over their hearts.

“It wasn’t planned or anything like that,” Stokes said. “To me, for them to stand up in the middle of it, I thought it was disrespectful, and my kids did too, so they stayed kneeling and put their hand over their chest.”

While his players were not kneeling in protest, Stokes said he supports the NFL players that chose to kneel.

“I support the guys for standing up for their rights,” Stokes said. “If they locked hands during the National Anthem or they don’t stand, show them support because that’s what they believe in.”