Subala Upanishad p7

p7

saubālabījabrahmopaniṣannāpraśāntāya dātavyā nāputrāya nāśiṣyāya nāsaṃvatsara-rātroṣitāya nāparijñātakulaśīlāya dātavyā naiva ca pravaktavyā | yasya deve parā bhaktiryathā deve tathā gurau | tasyaite kathitā hyarthāḥ prakāśante mahātmana ityetannirvāṇānuśāsanamiti vedānuśāsanamiti vedānuśāsanam ||

"This Subāla-Bīja-Brahma-Upanishaḍ should neither be given out nor taught to one who has not controlled his passions, who has no sons, who has not gone to a Guru, and having become his disciple has not resided with him for a year, and whose family and conduct are not known. These doctrines should be taught to him who has supreme devotion to the Lord and as much to his Guru. Then these truths shine in his great soul. Thus is the exposition of Nirvāṇa; thus is the exposition of the Veḍas; yea, thus is the exposition of the Veḍas."