यत्तु कृत्स्नवदेकस्मिन्कार्ये सक्तमहैतुकम्।अतत्त्वार्थवदल्पं च तत्तामसमुदाहृतम्
yat tu kṛitsna-vad ekasmin kārye saktam ahaitukam atattvārtha-vad alpaṁ cha tat tāmasam udāhṛitam
But that which clings blindly to one idea as if it were all, without logic, truth, or insight, has its origin in darkness.
Translated by Shri Purohit Swami
But that which clings to one single effect as if it were the whole, without reason, without any foundation in Truth, and is trivial—that is declared to be Tamasic.
Translated by Swami Sivananda
Word meanings (from the gita/gita dataset)
yat—which; tu—but; kṛitsna-vat—as if it encompasses the whole; ekasmin—in single; kārye—action; saktam—engrossed; ahaitukam—without a reason; atattva-artha-vat—not based on truth; alpam—fragmental; cha—and; tat—that; tāmasam—in the mode of ignorance; udāhṛitam—is said to be