Bhagavad Gita, Chapter 2, Verse 49

Work with desire is far inferior to that performed with the mind undisturbed by thoughts of results. O Dhananjaya, seek refuge in this evenness of mind. Wretched are those whose motive to action is the fruit of action.

Working just to collect the payoff is the smaller version of what's possible here.

Krishna draws a real line between two kinds of effort: one chasing personal reward, one grounded in understanding. Holding tightly to results, this verse suggests, is actually a kind of poverty, not ambition.