Bhagavad Gita · 4.34

तद्विद्धि प्रणिपातेन परिप्रश्नेन सेवया।उपदेक्ष्यन्ति ते ज्ञानं ज्ञानिनस्तत्त्वदर्शिनः॥

tad viddhi praṇipātena paripraśhnena sevayā upadekṣhyanti te jñānaṁ jñāninas tattva-darśhinaḥ

Learn that knowledge by approaching the wise, by asking sincere questions, and by rendering service to them. The seers of truth, being established in knowledge, will impart it to you.

— Bhagavad Gita 4.34

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