Bhagwad Gita
Chapter 2, Verse 66
नास्ति बुद्धिरयुक्तस्य न चायुक्तस्य भावना।
न चाभावयतः शान्तिरशान्तस्य कुतः सुखम्।।2.66।।
One who is not in transcendental consciousness can have neither a controlled mind nor steady intelligence, without which there is no possibility of peace. And how can there be any happiness without peace?