Bhagavad Gita 18.19
ज्ञानं कर्म च कर्ता च त्रिधैव गुणभेदतः । प्रोच्यते गुणसङ्ख्याने यथावच्छृणु तान्यपि ॥
jñānaṃ karma ca kartā ca tridhaiva guṇa-bhedataḥ / procyate guṇa-saṅkhyāne yathāvac chṛṇu tāny api
Translation
Knowledge, action, and doer are declared to be threefold according to differences of the gunas in the science of the gunas. Hear of these as well, properly.
Reflection
Which faculty of yours are you most afraid to test against the three-color sieve?
Read this verse in its chapter: Chapter Eighteen
Krishna now turns the three-guna lens on three of the six elements he just named, jnana, karma, karta. Each will get its sattvika, rajasika, tamasika version. This is the architectural rhythm that has carried chapter seventeen and now drives the diagnostic spine of chapter eighteen. The promise is yatha-vat, accurately, properly, no shortcuts. The student is being given a complete diagnostic kit. By the end of the next several verses, a person should be able to look at any deed, the knowledge behind it, the act itself, the agent who performed it, and identify its texture without flattery.