Text 9

karyam ity eva yat karma
niyatam kriyate ’rjuna
sangam tyaktva phalam caiva
sa tyagah sattviko matah

Translation

O Arjuna, when one performs his prescribed duty only because it ought to be done, and renounces all material association and all attachment to the fruit, his renunciation is said to be in the mode of goodness.

Commentary by Srila Prabhupada 

Prescribed duties must be performed with this mentality. One should act without attachment for the result; he should be disassociated from the modes of work. A man working in Krishna consciousness in a factory does not associate himself with the work of the factory, nor with the workers of the factory. He simply works for Krishna. And when he gives up the result for Krishna, he is acting transcendentally.

Commentary by Sri Visvanatha Cakravarti Thakur

Performing the nitya karma (niyatam karma) thinking "this should be done" while rejecting doership and desired results is called sattvika tyaga. It is understood here that the result of renouncing the fruits and not renouncing the action in this sattvika tyaga is knowledge.