Bhagavad Gita 4.2
The Divine Kings knew it, for it was their tradition; then, after a long time, it was at last forgotten.
एवं परम्पराप्राप्तमिमं राजर्षयो विदुः।
स कालेनेह महता योगो नष्टः परन्तप॥evaṃ paramparāprāptamimaṃ rājarṣayo viduḥ|
sa kāleneha mahatā yogo naṣṭaḥ parantapa||
English translation (above): Shri Purohit Swami (1935), public domain. Sanskrit text via github.com/gita/gita (Unlicense).