Chapter 14 · The Three Qualities · Krishna said
Bhagavad Gita 14.13 — Signs of tamas
अप्रकाशोऽप्रवृत्तिश्च प्रमादो मोह एव च। तमस्येतानि जायन्ते विवृद्धे कुरुनन्दन ॥
aprakāśo'pravṛttiśca pramādo moha eva ca | tamasyetāni jāyante vivṛddhe kurunandana ||
Meaning
When tamas increases, darkness of mind, inactivity, carelessness and delusion arise.