Bhagavad Gita 4.18

कर्मण्यकर्म य: पश्येदकर्मणि च कर्म य: |
स बुद्धिमनुष्येषु स युक्त: कृत्स्नकर्मकृत्

Translation

Those who see action in inaction and inaction in action are truly wise amongst humans. Although performing all kinds of actions, they are yogis and masters of all their actions.