यदग्रे चानुबन्धे च सुखं मोहनमात्मनः ।निद्रालस्यप्रमादोत्थं तत्तामसमुदाहृतम् ॥
yadagre cānubandhe ca sukhaṃ mohanamātmanaḥ |nidrālasyapramādotthaṃ tattāmasamudāhṛtam ||
The happiness that bewilders the self, both at the start and in its aftermath, and that arises from sleep, laziness and negligence, is declared to be tamasic.
Explanation
Krishna is finishing his threefold account of happiness (sukha), after the sattvic and rajasic kinds. Tamasic happiness is dull and deluding (moha) from beginning to end, and it comes from sleep, laziness (ālasya) and heedless negligence (pramāda). Tamas is the guṇa, or strand of nature, linked with inertia and ignorance.