Verse
कर्मणो ह्यपि बोद्धव्यं बोद्धव्यं च विकर्मणः ।अकर्मणश्च बोद्धव्यं गहना कर्मणो गतिः ॥
One has to understand about action as well as to understand about wrong action and about inaction one has to understand; thick and tangled is the way of works.
Gītā 4·17