The 30-year-old Davis, in his 10th National Football League season, did not return for the second half of the Bills 31-20 week-two loss to the Los Angeles Chargers.
He pulled himself out of the game.
Davis, who made his National Football League debut 10 years ago, said he knew he could no longer physically compete at the highest level.
"I meant no disrespect to my teammates and coaches. the season is long, and it's more important for me and my family to walk away healthy than to willfully embrace the warrior mentality and limp away too late".
"This was an overwhelming decision but I'm at peace with myself", it read. The Bills were down 28-6 at the time, so some frustrations may well have boiled over, but this goes above and beyond mere frustration. Davis was a noticeable absentee after half-time and it was later confirmed he told his team-mates he was retiring.