Buffalo Bills legend Jim Kelly announced Thursday morning his oral cancer has returned. 

In a statement, the Hall of Fame quarterback and his family ask for prayers. 

"I continuously talk about the four F's. Faith, Family, Friends and Fans. With all of you by my side, we will fight and win this battle together," he says. 

The Bills, in a separate statement, call Kelly a "tough and courageous man and we know he will fight this battle with strength and determination. The Buffalo Bills will support the Kelly family during this trying time and we ask our fans to pray for the family as Jim begins the treatment process and the road to recovery." 

Recent testing showed signs of the disease. Kelly was first diagnosed in 2013 and the cancer went into remission twice, the last time in 2014.