President Donald Trump’s rally in Huntsville, Alabama, Friday night was supposed to gin up support for Sen. Luther Strange, who’s running to permanently fill the Senate seat he was appointed to after Jeff Sessions ascended to attorney general.

Trump ended up complaining about football.

As is often typical for a Trump rally, the event Friday was structured more like a Fox News opinion show: a little politics, a little current events, a little culture war. At one point, Trump referenced the recent trend — started by former San Francisco 49ers quarterback Colin Kaepernick — of black football players taking a knee during the national anthem in protest.

“Wouldn’t you love to see one of these NFL owners, when somebody disrespects our flag, to say ‘get that son of a bitch off the field?’” Trump said to roaring applause. Trump said if owners fired a player for protesting the anthem, they would become “the most popular person in the country. Because that is a total disrespect of our heritage.” (Kaepernick, after leaving his contract with the 49ers, has not been able to secure a position on another team.)

Trump said these players are “ruining the game.” On Saturday, he reiterated these comments on Twitter.

If a player wants the privilege of making millions of dollars in the NFL,or other leagues, he or she should not be allowed to disrespect.... — Donald J. Trump (@realDonaldTrump) September 23, 2017

...our Great American Flag (or Country) and should stand for the National Anthem. If not, YOU'RE FIRED. Find something else to do! — Donald J. Trump (@realDonaldTrump) September 23, 2017

And in a week when a former NFL player who had been convicted of murder and committed suicide was found to have brain damage, adding to the evidence that concussions are severely affecting players’ brains, Trump argued that focusing on athletes’ brain injuries is also “ruining the game.” Football players, he said, “want to hit.”

NFL commissioner Roger Goodell responded Saturday morning, but didn’t specifically mention Trump or the anthem protests. “Divisive comments like these demonstrate an unfortunate lack of respect for the NFL, our great game and all of our players, and failure to understand the overwhelming force for good our clubs and players represent in our communities,” he said.

New NFL statement pic.twitter.com/XHPgVvPPfH — Brian McCarthy (@NFLprguy) September 23, 2017

The president’s entire rally was, in keeping with his rallies since the campaign, wide-ranging and often rambling: