Bhagavad Gita 15.20

Thus, O sinless one, I have revealed this most mystic knowledge to thee. He who understands it gains wisdom and attains the consummation of life.

इति गुह्यतमं शास्त्रमिदमुक्तं मयाऽनघ।एतद्बुद्ध्वा बुद्धिमान्स्यात्कृतकृत्यश्च भारत॥

iti guhyatamaṃ śāstramidamuktaṃ mayā'nagha|etadbuddhvā buddhimānsyātkṛtakṛtyaśca bhārata||

English translation (above): Shri Purohit Swami (1935), public domain. Sanskrit text via github.com/gita/gita (Unlicense).