Bhagavad Gita 18.67

इदं ते नातपस्काय नाभक्ताय कदाचन |
न चशुश्रूषवे वाच्यं न च मां योऽभ्यसूयति

Translation

This instruction should never be explained to those who are not austere or to those who are not devoted. It should also not be spoken to those who are averse to listening (to spiritual topics), and especially not to those who are envious of Me.