In 1967, now more than 50 years ago, Muhammad Ali held his “Cleveland Summit,” where leading black athletes including Jim Brown, Bill Russell, and Kareem Abdul-Jabbar (then named Lew Alcindor) met with Ali over his refusal to be drafted to the U.S. Army.

In 2018, Abdul-Jabbar sees shades of Ali’s social activism in former NFL quarterback Colin Kaepernick. Last year, Abdul-Jabbar penned the essay when Sports Illustrated awarded Kaepernick its Muhammad Ali Legacy Award.

Kaepernick is still without a team, and is engaged in a lawsuit against NFL owners over collusion. Last week, the Carolina Panthers signed safety Eric Reid, who was the first player to join Kaepernick’s kneeling protest. Some hopefuls saw it as a sign that teams might be ready to sign Kaepernick again, but that is unlikely. As ESPN NFL analyst and former NFL executive Louis Riddick told Yahoo Finance last week that NFL teams “look at Colin Kaepernick right now, from a football perspective, as being something that can negatively affect the bottom line, negatively affect consumer purchasing habits, and they don’t want to deal with that. That’s just a fact.”

Kaepernick’s career in the NFL is almost surely over, and Abdul-Jabbar says that’s what makes him admire Kaepernick so deeply.

“I think Colin did a pretty brave thing sacrificing his career to make statements about things that are very important to him,” Abdul-Jabbar tells Yahoo Finance. “He used his platform to do that, and he paid a tremendous price for it. I think Nike should be commended for stepping up and giving him some support, and making it possible for people to see what Colin is really about, and I’m totally supportive of that. I thought he used his platform to make a peaceful and poignant point about an issue that was very important to him. And being willing to sacrifice like that really says a lot for someone’s character.”

That is high praise coming from Abdul-Jabbar, who had such a storied sports career that an auction of some of his personal memorabilia is expected to bring in millions of dollars.

Goldin Auctions is selling off a treasure trove of Abdul-Jabbar’s personal effects, including his championship rings, game-worn jerseys, and even a childhood Little League trophy. Abdul-Jabbar says he’s doing it because “I’m not in the museum business, so what am I going to do with it? It would take over a large portion of my home if I displayed it in my home.” A portion of the proceeds will go to support his charity, Skyhook Foundation, which sends kids to camp to learn STEM (science, technology, engineering and math).