Kaṭha Upaniṣad 256

256

sā hṛnmanīṭ kathaṃ prāpyata iti tad artho yoga ucyate -- yadā yasmin kāle svaviṣayebhyo nivartitānyātmany eva pañca jñānāni / jñānārthatvāc chrotrādīnīndriyāṇi jñānāny ucyante / avatiṣṭhante saha manasā yad anugatāni, tena saṃkalpādivyāvṛttenāntaḥkaraṇena / buddhiś cādhyavasāyalakṣaṇā na viceṣṭati svavyāpāreṣu na viceṣṭate na vyāpriyate, tām āhuḥ paramā gatim ///2,3.10 //

When the five organs of perception become still, together with the mind, and the intellect ceases to be active: that is called the highest state.