Bhagavad Gita 18.32

अधर्मं धर्ममिति या मन्यते तमसाऽऽवृता।सर्वार्थान्विपरीतांश्च बुद्धिः सा पार्थ तामसी ॥१८.३२॥

adharmaṃ dharmamiti yā manyate tamasā’’vṛtāsarvārthānviparītāṃśca buddhiḥ sā pārtha tāmasī

That intellect, O Arjuna, which is enveloped in darkness and sees Adharma as Dharma and all things perverted, is Tamasic (dark).

गीता