Bhagwad Gita
Chapter 6, Verse 45
प्रयत्नाद्यतमानस्तु योगी संशुद्धकिल्बिषः।
अनेकजन्मसंसिद्धस्ततो याति परां गतिम्।।6.45।।
But when the yogi engages himself with sincere endeavor in making further progress, being washed of all contaminations, then ultimately, after many, many births of practice, he attains the supreme goal.