Bhagavad Gita · 18.67

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

idaṁ te nātapaskāya nābhaktāya kadāchana na chāśhuśhrūṣhave vāchyaṁ na cha māṁ yo 'bhyasūyati

This should never be spoken to one who is without austerity, who is not devoted, who does not wish to hear, or who speaks ill of Me.

— Bhagavad Gita 18.67

Source: Sacred-Texts.com (Sanskrit) + Bhagavad-Gita.io (translations)