The Yoga of Liberation by Renunciation

Krishna explains the tamasic doer. 'Ayuktaḥ prākṛtaḥ stabdhaḥ śaṭho naiṣkṛtiko 'lasaḥ'—unsteady (ayuktaḥ), vulgar (prākṛtaḥ), stubborn (stabdhaḥ), deceitful (śaṭhaḥ), malicious (naiṣkṛtikaḥ), lazy (alasḥ). 'Viṣādī dīrgha-sūtrī ca kartā tāmasa ucyate'—despondent (viṣādī), procrastinating (dīrgha-sūtrī), the doer (kartā) is called (ucyate) tamasic (tāmasaḥ). This is the tamasic doer: unsteady, uncultured, stubborn, deceitful, malicious, lazy, despondent, and procrastinating. This is the lowest kind of doer: driven by tamas (ignorance), which creates delusion, negligence, and harmful qualities. Unlike the sattvic doer (detached, balanced) and the rajasic doer (passionate, active), the tamasic doer is ignorant, lazy, and potentially harmful. This doer is bound by ignorance and negative qualities.