Bhagavad Gita 18.25 Chapter 18, Verse 25

अनुबन्धं क्षयं हिंसामनपेक्ष्य च पौरुषम् ।
मोहादारभ्यते कर्म यत्तत्तामसमुच्यते ॥१८.२५॥

anubandhaṃ kṣayaṃ hiṃsāmanapekṣya ca pauruṣam
mohādārabhyate karma yattattāmasamucyate

Meaning

Action begun out of delusion, without regard for consequences, loss, harm to others or one's own capacity, is called tamasic.

Newly written by Bhajan Dhun — scholarly review in progress.

Reference: Bhagavad Gita 18.25 (Chapter 18, Liberation through Renunciation (Moksha Sannyasa Yoga), Verse 25)