Thou hast power only to act not over the result thereof. Act thou therefore without prospect of the result and without succcumbing to inaction
(
The translation follows thus

Karmani ave adhikars te
--you have the power to act only
ma phalesu kadachana
--you do not have the power to influence the result
ma karmaphal hetur bhoo
--therefore you must act without the anticipation of the result
ma sangostu akramani
--without succumbing to inaction
)