Bhagavad Gita 18.32
And that which, shrouded in Ignorance, thinks wrong to be right, and sees everything perversely, O Arjuna, that intellect is ruled by Darkness.
अधर्मं धर्ममिति या मन्यते तमसाऽऽवृता।सर्वार्थान्विपरीतांश्च बुद्धिः सा पार्थ तामसी॥adharmaṃ dharmamiti yā manyate tamasā''vṛtā|sarvārthānviparītāṃśca buddhiḥ sā pārtha tāmasī||
English translation (above): Shri Purohit Swami (1935), public domain. Sanskrit text via github.com/gita/gita (Unlicense).