Bhagavad Gita Chapter 14, Verse 16

कर्मणः सुकृतस्याहुः सात्त्विकं निर्मलं फलम् | रजसस्तु फलं दुःखमज्ञानं तमसः फलम् ||

karmaṇaḥ sukṛtasyāhuḥ sāttvikaṁ nirmalaṁ phalam rajasas tu phalaṁ duḥkham ajñānaṁ tamasas phalam

They say the result of good action is sattvic and pure. The result of rajas is suffering, and the result of tamas is ignorance.

Krishna explains the fruits of actions performed under each guna: 'Karmaṇaḥ sukṛtasyāhuḥ sāttvikaṁ nirmalaṁ phalam'—they say (āhuḥ) the result (phalam) of good action (sukṛtasya) is sattvic (sāttvikam) and pure (nirmalam). 'Rajasas tu phalaṁ duḥkham'—the result (phalam) of rajas is suffering (duḥkham). 'Ajñānaṁ tamasas phalam'—the result (phalam) of tamas is ignorance (ajñānam). This reveals the consequences of each guna: actions in sattva bring pure results, actions in rajas bring suffering, actions in tamas bring ignorance. Understanding this helps you see why it's important to cultivate sattva and eventually transcend all three. Even though sattva brings good results, the ultimate goal is to transcend all gunas and act without being bound by any mode.