Bhagavad Gita
18.19

ज्ञानं कर्म च कर्ता च त्रिधैव गुणभेदतः | प्रोच्यते गुणसंख्याने यथावच्छृणु तान्यपि ||

jñānaṁ karma ca kartā ca tridhaiva guṇa-bhedataḥ proc yate guṇa-saṅkhyāne yathāvac chṛṇu tāny api

Translation

Knowledge, action, and the agent are declared in the Samkhya doctrine to be threefold according to the distinction of the gunas. Hear these distinctions duly.

Interpretation

The triple guna-analysis now extends to knowledge, action, and the agent — the three fundamental constituents of any karma. Each of these three is itself threefold (sattvic, rajasic, tamasic). This systematic elaboration reveals that the quality of the entire karmic act — what we know, what we do, who we take ourselves to be in doing it — is colored by the dominant guna. To transform action, one must transform all three: knowledge must become sattvic, action must become sattvic, and the agent's self-understanding must become sattvic.