इदं ते नातपस्काय नाभक्ताय कदाचन ।न चाशुश्रूषवे वाच्यं न च मां योऽभ्यसूयति ॥
idaṃ te nātapaskāya nābhaktāya kadācana |na cāśuśrūṣave vācyaṃ na ca māṃ yo'bhyasūyati ||
You must never speak this to one who lacks austerity, nor to one without devotion, nor to one who does not wish to listen, nor to anyone who finds fault with me.
Explanation
Krishna, near the end of the Gita, tells Arjuna whom this teaching should not be shared with. He names four cases: someone without self-discipline or austerity (tapas), without devotion (bhakti), unwilling to listen, or hostile to Krishna. The point is usually taken to be that such teaching bears fruit only where there is openness and respect; traditions differ on how strictly to apply these conditions.