Verse
यदग्रे चानुबन्धे च सुखं मोहनमात्मनः ।निद्रालस्यप्रमादोत्थं तत्तामसमुदाहृतम् ॥
That pleasure of which delusion is the beginning and delusion is the consequence, which arises from sleep, indolence and ignorance, that is declared tamasic.
Gītā 18·39