Chapter 4 · Knowledge and Renunciation of Action · Krishna said
Bhagavad Gita 4.18 — Inaction in action
कर्मण्यकर्म यः पश्येदकर्मणि च कर्म यः। स बुद्धिमान्मनुष्येषु स युक्तः कृत्स्नकर्मकृत् ॥
karmaṇyakarma yaḥ paśyedakarmaṇi ca karma yaḥ | sa buddhimānmanuṣyeṣu sa yuktaḥ kṛtsnakarmakṛt ||
Meaning
One who sees inaction in action and action in inaction is wise among people; such a person is steady in yoga and has done all that needs doing.