Bhagavad Gita 18.25
अनुबन्धं क्षयं हिंसामनपेक्ष्य च पौरुषम्। मोहादारभ्यते कर्म यत्तत्तामसमुच्यते।।18.25।।
anubandhaṃ kṣayaṃ hiṃsāmanapekṣya ca pauruṣam| mohādārabhyate karma yattattāmasamucyate||18.25||
anubandham kshayam himsamanapekshya ca paurusham mohadarabhyate karma yattattamasamucyate18.25
Meaning
That action undertaken from delusion, without regard for consequences, loss, injury to others, or one's own ability — that is tamasic action.
जो कर्म परिणाम, हानि, हिंसा और सामर्थ्य (पौरुषम्) का विचार न करके केवल मोहवश आरम्भ किया जाता है, वह कर्म तामस कहलाता है।
This is verse 25 of 78 in Chapter 18 (Moksha Sannyasa Yoga) of the Bhagavad Gita.