Bhagavad Gita · 6.45

प्रयत्नाद्यतमानस्तु योगी संशुद्धकिल्बिषः।अनेकजन्मसंसिद्धस्ततो याति परां गतिम्॥

prayatnād yatamānas tu yogī saṁśhuddha-kilbiṣhaḥ aneka-janma-saṁsiddhas tato yāti parāṁ gatim

But the yogi who strives with great effort, purified of sins, perfected through many births, then attains the supreme goal.

— Bhagavad Gita 6.45

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