Bhagavad Gita, Chapter 14, Verse 8

And know Tamas to be born of ignorance, stupefying all embodied beings; it binds fast, O descendant of Bharata, by miscomprehension, indolence, and sleep.

The heaviest of the three forces named here is described as working through real neglect, not active harm.

Tamas doesn't need dramatic wrongdoing to do its damage, laziness and sleep are named as enough on their own. Real danger here comes from what's left undone, not just from what's done wrong.