Bhagavad Gita 17.19

मूढ़गृहेनात्मनो यत्पीडया क्रियते तप: |
प्रस्योत्सादनार्थं वा तत्तमसमुदाहृतम्

Translation

That penance which is performed by persons who have confused thoughts and which involves torturing oneself and causing harm to others is called Tamoguni.