Matthews' response Thursday to a reporter from his verified account was captured by a screen grab.
The tweet has since been deleted.
Titans WR Rishard Matthews said on Twitter that he would quit playing in the NFL if they began requiring teams to stand for the National Anthem.
The NFL and NFLPA released a joint statement Wednesday confirming that there has been no change to the policy that recommends, but doesn't require, players to stand for the anthem.
"No, I will be done playing football", Matthews responded.
Since President Trump's September 23 criticism of NFL players' national anthem protests, Matthews has vowed to continue kneeling until the President apologizes.
Tight end Delanie Walker said he received death threats after the Seahawks game after stating that fans who felt disrespected by athletes using their platform to protest don't have to come to games. The protests started after former San Francisco 49ers quarterback Colin Kaepernick started kneeling to protest police mistreatment of African Americans. The receiver explained he didn't want his protest seen as a "publicity stunt". Why is it anti-American to exercise the right of free speech, while many drape themselves in the flag hypocritically while trying to deny others the freedom to exercise that right?