We must all live together and work together no matter what race or nationality. If you have an opportunity to accomplish something that will make things better for someone coming behind you, and you don't do that, you are wasting your time on this earth.
Source, in full
Another excerpt from the Tris Speaker speech – featuring a much more familiar version of the "wasting your time" warning – as quoted in "Standing Cheer for Roberto" by Houston Chronicle sportswriter John Wilson, in The Sporting News (February 20, 1971), p. 44.
Notes from Wikiquote
Comment: In contrast to so many versions of Clemente's "wasting your time on this earth" quote that have circulated over the years, this one and the one published by the Houston Post three weeks earlier have the distinction of being written by persons actually present at the speech in which Clemente uttered the now ubiquitous phrase. The fact that two eyewitness accounts are so different – in terms, both of wording and of the latter's crucial inclusion of the now familiar altruistic emphasis – would suggest that both are genuine and that Clemente simply repeated the phrase in different contexts at different points during his talk. If so, it should come as no surprise, given both the circumstances of Clemente's death and the nature of his off-field concerns, that it is the latter version, along with countless variations thereof, which has gained more currency.