Bhagavad Gita 2.66

नास्ति बुद्धिरयुक्तस्य न चायुक्तस्य भावना।न चाभावयतः शान्तिरशान्तस्य कुतः सुखम् ॥२.६६॥

nāsti buddhirayuktasya na cāyuktasya bhāvanāna cābhāvayataḥ śāntiraśāntasya kutaḥ sukham

There is no knowledge of the Self for the unsteady, and no meditation is possible for the unsteady, and no peace for the unmeditative, and how can there be happiness for one who has no peace?

गीता