B.G 18.67

इदं ते नातपस्काय नाभक्ताय कदाचन। न चाशुश्रूषवे वाच्यं न च मां योऽभ्यसूयति ॥६७॥

idaṁ te nātapaskāya nābhaktāya kadācana। na cāśuśrūṣave vācyaṁ na ca māṁ yo'bhyasūyati ॥67॥

[इदं (idaṁ) - this; ते (te) - to you; न (na) - not; अतपस्काय (atapaskāya) - to one without austerity; न (na) - not; अभक्ताय (abhaktāya) - to one without devotion; कदाचन (kadācana) - ever; न (na) - not; च (ca) - and; अशुश्रूषवे (aśuśrūṣave) - to one who is not willing to listen; वाच्यम् (vācyam) - to be spoken; न (na) - not; च (ca) - and; माम् (mām) - me; यः (yaḥ) - who; अभ्यसूयति (abhyasūyati) - is envious;]

This teaching should never be imparted to those who lack austerity, devotion, or willingness to listen, nor to those who are envious of Me.