Boos could be heard from the crowd as the Dallas Cowboys took a knee with owner Jerry Jones.
Singer Jordin Sparks is sending a message of her own about the "take a knee" controversy that's dividing the nation.
Read: WWII Vet, 97, Takes Knee in Support of NFL Protests: 'Those Kids Have Every Right to Protest'
The former American Idol winner wrote on her left hand a reference to Proverbs 31:8-9 as she belted out the national anthem at Monday night’s Dallas Cowboys game against the Arizona Cardinals.
The verses read, "Speak up for those who cannot speak for themselves,” and "speak up and judge fairly."
Moments before the start of the game the Cowboys, nicknamed "America’s team," all took a knee with owner Jerry Jones, a fervent supporter of President Trump.
Boos could be heard from the sellout crowd, which got the attention of Trump, who took to Twitter to voice his displeasure at the gesture.
“The booing at the NFL football game last night, when the entire Dallas team dropped to its knees, was loudest i have ever heard. Great anger,” the president tweeted.
The booing at the NFL football game last night, when the entire Dallas team dropped to its knees, was loudest I have ever heard. Great anger
— Donald J. Trump (@realDonaldTrump) September 26, 2017
But when Sparks sang the national anthem, both the Cowboys and the Cardinals stood with their arms linked in solidarity.
Trump also tweeted about that.
But while Dallas dropped to its knees as a team, they all stood up for our National Anthem. Big progress being made-we all love our country!
— Donald J. Trump (@realDonaldTrump) September 26, 2017
By Tuesday morning, Trump continued to slam the NFL for letting players kneel.
The NFL has all sorts of rules and regulations. The only way out for them is to set a rule that you can't kneel during our National Anthem!
— Donald J. Trump (@realDonaldTrump) September 26, 2017
During a news conference at the White House Rose Garden Tuesday afternoon, Trump was asked by reporters about the national anthem protests and his apparent conflict with the sports world.
"For people to disrespect [the military] by kneeling during the playing of the national anthem, I think is disgraceful," Trump said.
Actor Antonio Sabato, Jr., a Trump supporter, weighed in on the controversy during an appearance on the Fox Business Network Tuesday
“It is disrespectful to our men and women who have fought for our freedom and it is not the right place to do so,” he stated.
The widow of Pat Tillman, the NFL player-turned-U.S.-Army Ranger who was killed by friendly fire in Afghanistan in 2004, has slammed the president for "politicizing" her husband's death.
Read: President Trump Rescinds Stephen Curry's Invitation to the White House
"As a football player and soldier, Pat inspired countless Americans to unify," Marie Tillman wrote in a statement to CNN Tuesday. "Pat's service, along with that of every man and woman's service, should never be politicized in a way that divides us. We are too great of a country for that. Those that serve fight for the American ideals of freedom, justice and democracy. They and their families know the cost of that fight. I know the very personal costs in a way I feel acutely every day.”
"The very action of self-expression and the freedom to speak from one's heart — no matter those views — is what Pat and so many other Americans have given their lives for," she added. "Even if they didn't always agree with those views."
Tillman played for the Arizona Cardinals but left football and enlisted in the U.S. Army following the September 11 attacks. He served tours in both Iraq and Afghanistan before his death.
Watch: 'The Voice' Star Meghan Linsey Reveals Why She Decided to Kneel After National Anthem
