Bhagavad Gita 18.25

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

anubandhaṃ kṣayaṃ hiṃsāmanapekṣya ca pauruṣammohādārabhyate karma yattattāmasamucyate

That action which is undertaken from delusion, without regard for the consequences, loss, injury, and one's own ability, is declared to be Tamasic (dark).

गीता