For the past two Titans' games, the veteran wideout has remained in the team's locker room during the anthem.
Matthews quickly deleted the tweet Thursday before practice, but his comments had been caught by a screen grab.
He responded with a tweet: "No I will be done playing football".
The protests by Matthews started following a torrent of criticism from President Donald Trump, who attacked players for not standing during the anthem. However, that changed after Trump referred to protesting players as 'sons of b******' during a speech in Alabama back in September.
"I'm exhausted of hearing, 'Stick to sports.' It comes down to right and wrong in this world", Rishard Matthews told ESPN in September. "If you see wrong and don't say anything, that's wrong".
'I Will Forever Salute You, ' Matthews wrote in the caption.
A former college teammate of Colin Kaepernick, the free agent quarterback who first began protesting injustice by kneeling during the anthem last season, Matthews has also donated $75,000 to less fortunate communities. As minorities, what do you want to happen before we say anything? Commissioner Roger Goodell, NFLPA executive director DeMaurice Smith and player leadership will attend league meetings next week to discuss how to progress on social issues and discuss the subject of protesting during the anthem in a larger scale.
The NFL had to then release a statement Wednesday clarifying what he meant.
"Like many of our fans, we believe that everyone should stand for the national anthem", he said.
"Sometimes people, as you all know, tweet some ignorant things out at some moments and that was an ignorant thing I tweeted out at that given moment", Matthews said.
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