Jim Brown has also said he is with Kaepernick "100% in his sincerity and his right to bring these things out."
Pro Football Hall of Fame running back Jim Brown offered a measured criticism of Colin Kaepernick's national anthem protest, telling TIME he takes issue with Kaepernick demonstrating during the national anthem.
Brown's comments appear in a TIME cover story about Kaepernick's ongoing protest of racial inequality and police violence. During the preseason, the 49ers quarterback protested by sitting during the national anthem, and in San Francisco's final preseason game and through the first two weeks of the regular season, Kaepernick has chosen to instead kneel during the anthem.
"I would not challenge our flag," Brown told TIME's Sean Gregory. "I would not do anything that has to do with respecting the flag or the national anthem. I don't think it's appropriate."
A number of other athletes, including several NFL players, have followed Kaepernick's lead, protesting during the pregame performance of the “Star-Spangled Banner.”
Brown, who was outspoken on social issues during his career, supports Kaepernick's right to protest. Last weekend, he said Kaepernick had reached out to him and that he offered the quarterback his support.
"Colin is a very beautiful human being," Brown said, according to Syracuse.com. "He reached out to me. He got my telephone number and he called me. We had a great conversation. I'm with him 100% in his sincerity and his right to bring these things out."
Brown, who played in the NFL from 1957 to '65, has long been one of the sports world's most prominent civil rights activists. In the 1960's, he helped lead a generation of black athletes, such as Muhammad Ali and Kareem Abdul-Jabbar, who didn't hesitate to speak out on racism and injustice in America.
After serving as an Army Reserve officer following his graduation from Syracuse, Brown supported Ali when he refused to fight in Vietnam.
The former Cleveland Browns running back also explained to TIME why many athletes have been hesitant to take a stand on social issues.
"The agents tell these young people that you can get endorsements, you can get a lot of money, don't rock the boat," he told TIME. "Money becomes the objective, and individuals protect their image, make sure they have the right image so that they can represent corporations. And now what is happening is there seems to be a reversal."
Kaepernick and the 49ers will take on the Seahawks on Sunday.
Read TIME's full story on Kaepernick and his burgeoning movement in this week's magazine.