Bhagwad Gita
Chapter 18, Verse 67
इदं ते नातपस्काय नाभक्ताय कदाचन।न चाशुश्रूषवे वाच्यं न च मां योऽभ्यसूयति।।18.67।।
This confidential knowledge may not be explained to those who are not austere, or devoted, or engaged in devotional service, nor to one who is envious of Me.