Dave Stewart Mourns Rickey Henderson's Death, '1 Of The 5 Best Players To Ever Play'

Dave Stewart -- Rickey Henderson's former teammate and good friend -- is encouraging baseball fans everywhere to remember the outfielder in the wake of his death as a kind man who was "one of the five best players to ever play Major League Baseball."

Stewart sat down with TMZ Sports on Sunday -- just two days after Henderson passed away at 65 following a battle with pneumonia -- and he gushed over the Hall of Famer ... calling him "a tremendous human being."

Stewart says he first met Rickey when they were teenagers ... but formed a real bond with him when they turned pro.

The guys competed with each other on multiple MLB teams -- including the Oakland A's -- and Stewart made it clear, he loved his time with baseball's best-ever base stealer.

He told us Henderson always made him and his teammates laugh -- and was the kind of guy who would "give you the shirt off his back."

Even in retirement, Stewart said the two remained close. In fact, he told us he was working on a baseball business venture with Henderson just before he died.