Bhagavad Gita 18.28
While he whose purpose is weak, who is low-minded, stubborn, dishonest, malicious, lazy, despondent, and procrastinating—he may be assumed to be in darkness.
अयुक्तः प्राकृतः स्तब्धः शठो नैष्कृतिकोऽलसः।विषादी दीर्घसूत्री च कर्ता तामस उच्यते॥ayuktaḥ prākṛtaḥ stabdhaḥ śaṭho naiṣkṛtiko'lasaḥ|viṣādī dīrghasūtrī ca kartā tāmasa ucyate||
English translation (above): Shri Purohit Swami (1935), public domain. Sanskrit text via github.com/gita/gita (Unlicense).