यत्तु कृत्स्नवदेकस्मिन्कार्ये सक्तमहैतुकम् ।अतत्त्वार्थवदल्पं च तत्तामसमुदाहृतम् ॥
yattu kṛtsnavadekasminkārye saktamahaitukam |atattvārthavadalpaṃ ca tattāmasamudāhṛtam ||
But that knowledge which clings to a single thing as though it were the whole, which is without reason, without grasp of the truth, and narrow, is declared to be tamasic.
Explanation
Krishna is describing three kinds of knowledge according to the three qualities (guṇa) of nature. Tamasic (tāmasa) knowledge is dull and dark: it fixes on one object or action as if it were everything, offers no reasoning, and misses the real nature of things. It contrasts with the sattvic and rajasic kinds described in the two preceding verses.