Bhagavad Gita · 13.12

अध्यात्मज्ञाननित्यत्वं तत्त्वज्ञानार्थदर्शनम्।एतज्ज्ञानमिति प्रोक्तमज्ञानं यदतोऽन्यथा॥

adhyātma-jñāna-nityatvaṁ tattva-jñānārtha-darśhanam etaj jñānam iti proktam ajñānaṁ yad ato 'nyathā

Constancy in spiritual knowledge, and vision of the purpose of knowledge of truth — all this is declared to be knowledge, and what is contrary to this is ignorance.

— Bhagavad Gita 13.12

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