Former 49ers quarterback Colin Kaepernick was set to have a workout with the Seattle Seahawks on Monday, but the team canceled on the eve of the planned visit. The reason for the cancellation, a source with knowledge of the situation told Slate on Thursday, was that Kaepernick would not commit to ending his protest during the national anthem next season.

“There was a workout that was scheduled for about two weeks, travel was arranged, everything was set for the workout on Monday, then on the eve of the workout Seattle called and said … as a precondition he needs to stop kneeling,” the source told Slate. “He wouldn’t agree to it and they canceled it on Monday.”

ESPN’s Adam Schefter reported earlier on Thursday that a league source said the Seahawks had scheduled a workout with Kaepernick but canceled it after he declined to stop kneeling during the anthem. The NFL Network’s Ian Rapoport then reported that the workout was canceled because Kaepernick would not give Seattle “a plan” for his future advocacy.

#Seahawks brass, John Schneider and Pete Carroll, want Colin Kaepernick to consider how he wants to proceed on everything (not just anthem) and get together at a later date when his plans are formed. Clearly, Seattle has accepted players speaking out for what they believe. — Ian Rapoport (@RapSheet) April 12, 2018

The #Seahawks did postpone a tentatively scheduled workout with Colin Kaepernick, as @AdamSchefter reported. It was not because he said he declined to stop kneeling, tho. The team asked for his plan moving forward on how to handle everything and there was not a firm plan. — Ian Rapoport (@RapSheet) April 12, 2018

Seattle did not immediately respond to Slate’s requests for comment.

Kaepernick met with the Seahawks last May, but Seattle ultimately did not sign him despite coach Pete Carroll saying he was a “starter in this league.” “He’s capable of being a championship guy. He’s demonstrated that over years,” Carroll said at the time. “He’s been up and down in his career, but he’s shown enough ups that you know that he could do that. He presented himself really well.”

Last year, Kaepernick filed a grievance against the league and NFL teams for allegedly colluding to keep him out of the NFL last season because he protested police brutality by kneeling during the national anthem. In September, President Donald Trump said that any player who “disrespects our flag” was a “son of a bitch.”

Kaepernick, who hasn’t said much publicly about his collusion case, was awarded late last year with the ACLU of Southern California’s Eason Monroe Courageous Advocate Award. At the time, he said this:

We must confront systemic oppression as a doctor would a disease. You identify it, you call it out, you treat it, and you defeat it. We all have an obligation no matter the risk and regardless of reward to stand up for our fellow men and women who are being oppressed with an understanding that human rights cannot be compromised.” In the words of Frederick Douglass: “If there is no struggle, there is no progress.”

ESPN reported that NFL attorneys deposed Kaepernick as part of his collusion grievance the day after his reported canceled tryout.

Kaepernick’s former San Francisco 49ers teammate Eric Reid, who was the first player to join the quarterback’s protest, has had a similarly hard time signing with a team this offseason despite being one of the top safeties in free agency.

On Wednesday, Mike Florio reported that Reid had met with the Cincinnati Bengals on Monday. During that meeting, Florio said, Bengals owner Mike Brown told Reid he would be banning kneeling during the anthem this coming season and asked the player to respond. “Reid, caught off guard by the line of questioning, wasn’t willing to make a commitment on the spot,” according to Florio.